Caribbean Spawning Aggregations: Biology and Management Status

Transcription

A Protocol and Database for Monitoring Transient
Multi-species Reef Fish Spawning Aggregations
in the Meso-American Reef
WILLIAM D. HEYMAN1 and GREGORY ADRIEN2
'Department of Wildlife andFisheries Sciences
Texas A&M University
College Station, Texas 77843-2258 USA
2Adrien Consulting
16701 Leocrie Place
Woodbridge, Virginia 22191 USA
ABSTRACT
Most commercially important Caribbean reef fish species reproduce
within transient spawning aggregations in specific times and places. Fishers
have long recognized and capitalized on this behavior, and heavy fishing
pressure on spawning aggregations has led to declines and extirpations around
the Caribbean, particularly for Nassau grouper. For the same reason that
spawning aggregations are attractive to fishers, they are also an opportunity for
managers to monitor the populations. To maximize this opportunity, we
developed, tested, and produced a standardized protocol and accompanying
database for monitoring transient reef fish spawning aggregations. The
protocol includes both fisheries dependent and independent techniques for data
collection as well as physical oceanographic measures. The accompanying
database and user manual are designed intimately with the monitoring
protocol, providing easy data entry and data retrieval via generation of reports.
The system design allows upgradingto a web-based, SQL-server platform that
can handle data from aroundthe world. The protocol has been adopted by the
World Bank's Meso-American Barrier Reef Systems Project (MBRS) for
Belize, Mexico, Honduras and Guatemala.
KEY WORDS: Database, monitoring, spawning aggregations
Protocolo y Base de Datos para el Monitoreo de Agregaciones
Reproductivas Transitorias de Multiples Especies de
Peces Arrecifales en el Arrecife Mesoamericano
La mayor parte de las especies de peces arrecifales del Caribe con valor
comercial se reproducen en perfodos y lugares especfficos dentro de las
agregaciones reproductivas transitorias. Toda la produccidn reproductiva de
los peces que utilizan esta estrategia ocurre dentro de estas agregaciones. El
monitoreo de estas agregaciones puede servir como una manera eficiente de
monitorear estas poblaciones cuando pasan a traves de cuellos de botella
fisicos y temporales de gran importancia para sus ciclos de vida. No obstante,
hasta ahora no hay un protocolo de monitoreo sistematico generalmente
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57th Gulf and Caribbean Fisheries Institute
aceptado de estas agregaciones. Nosotros desarrollamos, probamos y produjimos un protocolo estandarizado y una base de datos que lo acompana para el
monitoreo de agregaciones reproductivas transitorias de peces arrecifales. El
sistema de monitoreo ha sido adoptado como estandar por los cuatro paisesdel
arrecife mesoamericano, Belice, Mexico, Honduras y Guatemala, a traves del
Proyecto de Sistemas de Arrecifes de Barrera Mesoamericanos del Banco
Mundial.
El protocolo y la base de datos fueron desarrollados en colaboracidn bajo
el liderazgo del Comite Nacional de Trabajo sobre Agregaciones Reproducti
vas de Belice y bajo los auspicios de The Nature Conservancy. El sistema se
encuentra en desarrollo y uso en Belice desde el afio 2000 y se usa para el
monitoreo de 17 sitios de agregaciones reproductivas de multiples especies
realizado por equipos de 8 organizaciones, gubernamentales y no gubernamentales, de Belice e internacionales.
El protocolo detalla metodos dependientes e independientes de pesquerias
asi como tecnicas de oceanografia flsica cuyo fin es monitorearlas agregacio
nes reproductivas. La base de datos en Access que lo acompafia y el manual
del usuario fueron disefiados en estrecha relacidn con el protocolo de monito
reo, para proveer un sistema sencillo de ingreso y recuperation de datos
mediante la generaci6n de informes. El sistema esta disefiado para ofrecer en
el future una aplicacidnadaptable con base en la red que utiliza una plataforma
de servidor SQL paramanejardatos de todo el mundo.
PALABRAS CLAVES: Agregaciones reproductivas, base de datos, monitoreo
INTRODUCTION
Tropical marine fisheries have sustained the livelihoods of coastal
communities throughout the Meso-American Reef and the wider Caribbean for
generations, but these resources are collapsing at an alarming rate throughout
the region (Safina 1995, NRC 1999, Jackson et al. 2001). Fisheries in the
Caribbean are diverse, generally targeting a variety of species simultaneously.
These multi-species fisheries are particularly difficult to monitor and manage
using traditional means. Of particular interest to the managers are the large
predatoryreef fishes such as snappers and groupers because oftheir value both
as fishery products-prized by diners worldwide-and as a "draw" in the tourism
industry-divers enjoy seeing large predators while diving and sport fishing.
These largerreef fishes generally reproducein transient spawning aggregations
that occur at specific times and places (Munro et al. 1973, Thompson and
Munro 1978, Johannes 1978, Thresher 1984, Domeier and Colin 1997, Colin et
al. 2003). Fishers have capitalized on this behavior by fishing intensively at
spawning aggregations (e.g., Craig 1969, Auil-Marshellek 1994). Early work
described the Nassau grouper fishery at Caye Glory, Belize, where as many as
300 boats captured over 2,000 kg of gravid groupers per day (Craig 1969).
More recent studies have further documentedaggregations ofother species and
at other times (e.g., Carter et al. 1994, Auil-Marshellek 1994, Heyman 1996,
Paz and Grimshaw 2001, Sala et al. 2001). Intensive fishing pressure on these
aggregations has led to declines and, in several cases, extirpations (Fine 1990,
Heyman, W.D. and G. Adrien GCFI:57 (2006)
Page 447
Sadovy 1994, PazandGrimshaw 2001,Sala et al.2001, Luckhurst2004).
Confounding the problems associated with declining fisheries resources
are the limited resources for the study, monitoring, and regulatory enforcement
of reef fisheries throughout the tropics. Though scientists have been aware of
spawning aggregations for many years, funding and resource constraints have
limited most studies to few locations, few techniques, short durations, and
focus on a single species at a time-generally groupers (e.g. Smith 1972, Colin
1992, Aguilar-Perera 1994, Carter et al. 1994, Aguilar-Perera and AguilarDavila 1996). These studies have provided excellent information about the
sites, species, and temporal aspect studied; however, the lack of consistency
among studies has resulted in insufficient data for broad-scale understanding of
spawning aggregation dynamics, or as a basis for management decisions. An
exception is the relatively well studied reef fish spawning aggregations in
Belize.
Anecdotal information from fishers and managers and the overall insuffi
ciency ofdataand management pertaining to spawningaggregations was cause
for concern. Individuals and organizations realized the still present threat to
Nassau grouper andthe valueofmulti-species reef fish spawning aggregations,
and formed the Belize Spawning AggregationsWorking Committee (BSAWC)
to foster good management. Given the large geographic spread and simultane
ous occurrencesofthe many aggregations in Belize this effort was challenging.
The BSAWC sponsoredvarious nation-wide assessments, starting in 2001 and
data from 17 sites in Belize were synthesized into an understandingoftransient
multi-species reef fish spawning aggregations at reef promontories (Heyman
and Requena 2002). Based in part on these data, a country-wide collaborative
effort of data collection, education, and consensus building culminated in
legislation that was enacted to conserve 11 of these sites within marine
reserves in Belize (GoB 2003a, Heyman 2004). The Belize example shows the
positive result of snareddatacollection and synthesis utilized for management.
Though fishers supportedthe legislation, they were particularlyconcerned
about the efficacy of the new laws. The BSAWC understood that a system to
monitor the populations status and to measure the success of management
programs was needed. The authors, working underthe auspices of The Nature
Conservancy, and with the input, testing, review, and support of the BSAWC,
worked collaboratively to develop a monitoring protocol, database, and data
sharing agreement that would serve the needs of Belize fishers and managers
alike. The BSAWC knew that Caribbean fisheries were facing similar issues,
and decided to expand the project scope to the Meso-American Reef (with
partial support provided by the Meso-American Barrier Reef Systems (MBRS)
project).
The system's broad design criteria were to provide reliable data for
monitoring and management decision-making on a large number of multispecies spawning aggregation sites, each having seasonal and annual monitor
ing needs. The system also needed a tool to facilitate the exchange of informa
tion and learning across sites and long time periods, and thus, the system
required the storage, retrieval, filtering, and output of various data sets. To be
truly useful, the system had to rely on existing technical, financial, and human
resources and be operated by local technicians of the four countries of the
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Meso-AmericanReef-Mexico, Belize, Guatemala, and Honduras.
After the initial development was completed, it was shared at the 55th
Annual Meeting of the Gulf and Caribbean Fisheries Institute in Tulum,
Mexico, November 2002. An open invitation was extended at that time for
user contributions to what has become this final (2004) product. This paper
describes the development, application, and use of the "Reef Fish Spawning
Aggregation Monitoring Protocol for the Meso-American Reef and the Wider
Caribbean" (Heyman et al. 2004) (hereafter referred to as the "Protocol") and
the corresponding "Spawning Aggregation Database,"hereafter referred to as
the "Database."
MATERIALS AND METHODS
The BSAWC sought involvement of all available institutional, financial,
and human resources to complete this project, including the Belize National
Government, local and international NGOs, fishing cooperatives, small-scale
commercial fishers, local marine reserves, international foundations, commu
nity groups,governmenttechnicians, marinereserve staff, fishers, dive guides,
students, oceanographers, marine scientists, marine biologists, map makers,
computer programmers, and computer operators. A complete list ofsupporting
institutions (14) and the names of contributing persons (over 100) are found
within the acknowledgementsof the Protocol.
The BSAWC recognized the existence of standardized fishery dependent
and independent monitoring techniques that had been or could be adapted for
spawning aggregation monitoring (e.g. Samoilys 1997a, Zeller 1998, Colin et
al. 2003, The Nature Conservancy 2003a,b). Techniques in the Protocol are
largely derived from these and other published techniques (see Table 1), but
with some modifications to account for the institutional, human, and financial
resource constraints of the implemented.
Various software packages and computer hardware platforms were
evaluated for their suitability to store, retrieve,and share spawning aggregation
monitoring data. Every effort was made to build a system that relies on
commonly available hardware and software within the region. Further, while
the system was designed to be operated initially by a network of individual
users on individual PCs, we recognized the need for eventual upgrading to a
web-based system to foster regional collaboration.
RESULTS AND DISCUSSION
Protocol Methodologies and Sample Results
Standardized metrics measured over time and compared among sites
provide managers with information on the health of various stocks and thus a
basis for management decisions (Lindeman et al. 2001).
Fishery-dependent monitoring — techniques evaluate catch/effort, length
frequency distribution, and gonosomatic indices based on measurements of
fish caught within an aggregation. Changes in population size structure can be
Heyman, W.D. and G.Adrien GCFI:57 (2006)
Page449
illustrated with these techniques, and provide an early indication of depletion.
Size frequency changes can appear before changes in numbers become
apparent Studies of age and growth, genetics, and histology require morphometric measures (e.g., length and weight of individuals and gonads) and
simultaneous sampling of various tissue or organ types for subsequent
laboratory analysis. Methods for extraction of otoliths for age determination;
gill, heart, or fin tissue for genetics; and gonads for histology or gonosomatic
indices are provided in the Protocol and other references (Table 1). These
metrics have been developed and standardized by many authors previously
(Table 1.). Fishery-dependent studies help provide an accurate assessment of
spawning times and strategies and assessments of population structure.
Fishery-independent techniques — are available for monitoring spawning
aggregations that are notbeing fished and to document behavior. Techniques
to evaluate physical and environmental factors that may affect spawning time,
or location, or egg dispersal areincluded.
Perhaps the simplest and most valuable techniques involve thedocumenta
tion of spawning aggregations using photography and video (Domeier and
Colin 1997, Colin et al. 2003). Photography and video have shown spawning
colorations, behaviors, andactual spawning events(e.g. Figure 1).
Underwater Visual Survey (UVS) techniques document reproductive
seasonality, abundance, and variability in the reef fish spawning aggregation
populations. The techniques described within the Protocol are similar to other
studies (e.g. Samoilys 1997b, Beets and Friedlander 1999, Sala et al. 2001,
Whaylen et al. 2004, Table 1) in which SCUBA divers collect data on the
abundance and sizes of fishes within aggregations. Through subsampling or
direct counts, observers can provide relatively accurate estimates of the
number of fish within particular aggregations.
For example, pair-wise
comparisons (n = 14) of Cubera snapper counts by two independent teams of
observers, diving at the same time within the same aggregation in Belize,
April-May 2004, were not significantly different. Sample data from Belize
collected using these techniques are provided in Figure 2. These data on two
commercially important reef fish species at a single spawning site show the
daily abundance and the year-round importance of the site as a spawning
ground, and have helped managers and fishers alike to agree on year-round
closures for several reef promontory spawning aggregation sites in Belize.
Using UVS, Beets and Friedlander (1999) showed significant increases in
abundance and sizes of red hind during six years following the closure of an
aggregation site. The BSAWC considers UVS techniques as described in the
Protocol to be sufficiently accurate for monitoring and for the basis of
management decisions.
There are a few caveats when usingUVS, however. The objectivesof the
monitoring program must be clear, particularly in a multi-species spawning
aggregation. By timing observations to coincide with specific seasonal, lunar,
and diel cycles, observers can dramatically increase their chances ofdocument
ing the aggregations accurately. Further, some species aggregate near the
bottom and toward the shelf edge (e.g., groupers), while other species, (e.g.
jacks) aggregate higher inthe water column. Observers must define sampling
Page 450
strategies and divide efforts to get accurate and repeatable counts on target
species. Natural variations in populations can also confoundUVS results. Six
years of monitoring a Cubera snapper aggregation at Gladden Spit, usingUVS
revealed significant seasonal and annual variations in the numbers of fish at
this aggregation site (Heyman et al. In review). Therefore, drawing conclu
sions about population trends using census data will require at least eight to ten
years for slower growing species such as large groupers, and we recommend
the precautionary principle.
Table 1. Techniques used in the Protocol with references to studies that
describe and use each.
Fishery Independent
Techniques
References and Examples
Photography and
Videography
Olsen & LaPlace 1979; Colin1992; Shapiro et al. 1993;
Tucker et al. 1993; Samoilys 1997a,b; Beets & Friedlander
1999; Sala et al. 2001; The Nature Conservancy 2003a. b;
Whaylen et al. 2004; Heyman et al. in rev.
Underwater Visual Survey
Colin et al. 1987; Colin 1992; Tucker et al. 1993; Carter et al.
1994; Domeier & Colin1997; Samoilys 1997a,b; Beets &
Friedlander 1999; Sala et al. 2001; Colin et al. 2003; The
Nature Conservancy 2003b; Medina-Quejet al. 2004;
Heyman et al. in rev.
Fish Tagging Studies
Carteret al. 1994; Sadovy etal. 1994; Luckhurst 1998; Zeller
1998; Bolden 2000
Bathymetric and Site
Mapping
and Site Descriptions
Colin et al. 1987;Colin 1992;Shapiroet al. 1993; Sadovy et
al. 1994; Aguilar-Perera &Aguilar-Davila 1996; Samoilys
1997a.b; Beets & Friedlander 1999; Sala et al. 2001; Colin et
al. 2003; Ecochard et al. 2003
Current Drogue Studies
Colin 1992
Physical Oceartographic Monitoring
Colin1992; Carter et al 1994; Heyman et al. in rev.
Fishery Dependent Techniques
Length:Frequency
Distribution
Olsen & LaPlace 1979; Colin et al. 1987; Claro 1981;
Crabtree & Bullock 1998; Colin 1992; Tucker et al. 1993;
Aguilar-Perera 1994; Carter et al. 1994; Sadovy et al. 1994;
Aguilar-Perera &Aguilar-Davila 1996; Domeier et al. 1996;
Sosa-Cordero & Cardenas-vldal 1996; Beets & Friedlander
1999; Garcia-Cagide et al. 2001; Burton 2002; Medina-Quej
et al. 2004
Catch per Unit Effort
Olsen & LaPlace 1979; Carter et al. 1994; Sadovy & Ecklund
1999; Sosa-Cordero & Cardenas-vldal 1996; Beets &
Friedlander 1999; Sala et al. 2001
Gonosomatic Index
Munro et al. 1973; Olsen & LaPlace 1979; Claro 1981;
Thresher 1984; Tucker et al. 1993; Carter et al. 1994; Sadovy
& Ecklund 1999; Sadovy et al. 1994; Domeier et al. 1996;
Garcia-Cagide & Garcia 1996; Beets & Friedlander 1999;
Garcia-Cagide et al. 1999; Garcia-Cagide et al. 2001; Burton
2002; The Nature Conservancy 2003b
Heyman, W.D. and G. Adrien GCFL57 (2006)
Page 451
B.
Figure 1. Photographs of spawning aggregations illustrating A. spawning
coloration in Nassau grouper, and B. Dog snapper spawning event (photo by
Douglas DavidSeifert).
.
Tagging studies — described in the Protocol use either simple identification
tags, and/or sonic tags and stationary sonic receivers. While somewhat
expensive, tagging studies can be very valuable, detailing both migration
patterns andpatterns of seasonality and site fidelity. Carter et al. (1994) found
a Nassau grouper swam ISO km from Belize to Mexico; Bolden (2000)
recorded one that swam 220 km to a spawning aggregation. Zeller (1998)
provides an excellent example of the utility of sonic tags in studies of site
fidelity, arrival and departure times of fish at an aggregation site, without
having to dive. Managers are urged to use identification tagsbefore investing
in much more expensive sonic tags, and are urged to consider tags where
diving would be too difficult
Page 452
Figure 2. The timing and abundance of spawning aggregations from daily
underwater visual surveys for A. Cubera Snapper and B. Nassau Grouper
during 2003 at Gladden Spit in Belize. (Data kindly provided by Friends of
Nature, Placencia, Belize).
Site maps anddescriptions — are valuable for monitoring and assessment of
spawning aggregations. A good base map is an essential tool if underwater
visual assessments willbe conducted regularly at a particular site. Maps of the
spawning aggregation sites can also be helpful in the design and zoning of
marine protected areas. Detailed methods for creating bathymetric maps that
include spawning aggregation sites are described in Ecochard et al. (2003).
Additional examples of maps andtechniques are referenced in Table 1.
Database Design and Structure
Software wasevaluated as a platform forthe aggregation monitoring data.
Thesoftware hadto be scalable andflexible to handle the variety of datatypes
and relationships. An automated database governed by a set of predefined
rules and standards for the capture, update, and retrieval of data was needed.
Microsoft Access 2000®, as a standalone application, offers all the basic
features needed to manage the Database, and also has features that will allow
for efficient data sharing and cost-effective upgrades. Access® is widely
available and offers additional features that other platforms do not and was
selected as the platform for the Database.
Heyman, W.D. and G. Adrien GCFL57 (2006)
Page 453
Access® has a built-in replication tool that can be used to distribute the
Database to all participating organizations (see Data Sharing, below). Further,
Access® can be usedto create an easy-to-use interface to a morescalable and
robust back-end database such as Microsoft SQL Server. Alternately, the entire
Database can be upgraded to SQL Server.
Minimumhardware requirements for operating the database are:
i) Pentium II personal computer (PC),
ii) 233 Mhz processing speed,
iii) 128Mb of RAM,
iv) 200 Mb ofharddisk space available,
v) VGA monitor,
vi) CD writer, and
vii) Internet connection anda reliable e-mail system
The Database stores data in a collection of related and linked tables. Data
is entered into these tables through pre-made, automated, digital forms (e.g.,
Figure 3, the Underwater Visual Survey Data entry form). The four database
entities are sites,surveytypes, organizations, and survey participants. Figure 4
shows the relationships among entities for the Visual Survey in an entityrelationship (ER) diagram. ER diagrams are popular high-level conceptual
data models used in the design of database applications. In many cases, data
entered for each entity is channeled into a data table for storage and retrieval.
In some cases, however, complex entities are broken down into smaller, more
stable tables for storage. Each table represents a group ofrelevant information
captured andmaintained together.
User Interface
The Database has been designed to be simple and easy to use, with heavy
emphasis placed on the design of the user interface. The data entry screens
(Figure 3) resemble the data sheets ofthe Protocol (Adrien 2003a). Whenever
possible, data entry has beenautomated using look-up tables to minimize user
entries ofnew species, new sites, or misspellings of existingentries.
Generating reports with the Database has also been designed to be simple
(Figure 5) yet not compromise the functionality and flexibility for the user.
The report section offers powerful ways to display survey data. Users can
specify parameters of interest for specific comparisons. For example, withina
single query, users can select to report either thecount orthe average of one or
many species at one or many sitesduring any specific yearor years (Figure 5).
Page 454
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Page 455
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Figure 4. Entity-Relationship (ER) diagram for Visual Survey data from the
Database illustratingthe relationships between entities. Arrows indicate the type
of relationship between entities with "1" (one) and "M" (many) at the end of each
arrow.
Page 456
57th Gulf and Caribbean Fisheries institute
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Figure 5. Visualsurvey report form from the Database illustrating an example
of a user-defined query. In this case, a query is requested that will illustrate all
entries of visual survey counts for two species (mutton snapper and Nassau
grouper) at two sites (Gladden Spit and Halfmoon Caye) over a four-year
period, 2000-2004. Users can also choose to see the data within Access, or
have the data directly exported to an Excel spreadsheet, or choose another tab
for queries using other data sets.
Data Sharing and Distribution
The database was designed with the understanding that many users, in
different areas could use the system on a stand-alone PC, but that these data
could be combined and shared. The eventual goal is to have the system
operational on an SQL server that is accessible to all users over the Internet on
a secure site. Web-based systems are morecomplex and costly to maintainand
update, so in the interim, the system relies on desktop systems for individual
organizations, each with a full copy of the database and all data. Data are
shared and updated by manual replication and synchronization of the various
databases (Figure 6). A detailed guide to Access® replication is freely
available (Adrien2003b). The drawback to the stand-alone system is synchro
nization. If synchronization does not occur regularly some organizations may
end up with outdated data, leadingto misinterpretation and incorrect reports.
Heyman, W.D. and G. AdrienGCFL57 (2006)
Page 457
Figure 6. Database structure and replication: the database is designed to be
able to be shared among multiple users. Using replication techniques, both the
main database (master) and the copies (replicas) can update each other
simultaneously.
CONCLUSIONS
As stated in the introduction to the Protocol:
"The purpose of the Protocol is to provide a standardized
methodology for the evaluation and routine monitoring and
conservation of transient multi-species spawning aggregations
along the Meso-American Reef and the wider Caribbean. This
document is intendedfor use by resource managers, conservation
ists, biologists, fishers, students and trained recreational divers.
'(Heyman et al. 2004).
The Database is an automated tool for data generated using the Protocol
from anywhere in the Caribbean, and it should be noted that it also can serve
the same purpose for the Asia-Pacific region. Despite the acceptance of the
Protocol and Database by users, we consider both as works in progress. Users
are encouraged to evaluate the systems critically, and to provide feedback to
the authors such that later releases can benefit.
Page 458
ACKNOWLEDGEMENTS
Thanks to Nicanor Requena for his extensive work on editing, testing,
sharing, and training using this protocol. Thanks to Douglas David Seifert for
providing use of Figure IB. Thanks to the Fisheries Department, Government
of Belize and the Belize Spawning Aggregations Working Committee for
collaboration andsupport. Thanks to Friends of Nature for data used in Figure
2. Thanks to the Summit and Oak Foundations for financial support. This
work was completed underthe auspices ofThe Nature Conservancy.
LITERATURE CITED
Adrien, G.E. [2003a]. Academic report to The John Hopkins University on
The Nature Conservancy's Spawning Aggregation Database. The Nature
Conservancy,Arlington, Virginia USA. 41 pp. Unpubl. MS.
Adrien, G.E. [2003b]. User's Guide for The Nature Conservancy's Spawning
Aggregation Database. The Nature Conservancy, Arlington, Virginia
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Spawning Locations for Atlantic Reef Fishes
off the Southeastern U.S.
GEORGE R. SEDBERRY, O. PASHUK, D.M. WYANSKI,
J.A. STEPHEN, and P. WEINBACH
South Carolina Department ofNatural Resources
P.O. Box 12559
Charleston, South Carolina 29422-2559 USA
ABSTRACT
Spawning condition was determined for 28 species of reef fish represent
ing 11 families (Balistidae, Berycidae, Carangidae, Centrolophidae, Haemulidae, Lutjanidae, Malacanthidae, Polyprionidae, Scorpaenidae, Serranidae,
Sparidae) collected off the Carolinas, Georgia and east coast of Florida
(including the Keys) in depths from 1 - 686 m. The presence of migratorynucleus oocytes, hydrated oocytes and/or postovulatory follicles was used to
indicate imminent or very recent spawning, and locations of capture of fishes
in spawning condition were mapped using GIS. Reproductive behavior was
observed from submersible for a few species. Most fishes were collected from
fishery-independent sampling, with time and location of collection accurately
recorded. Some specimens were sampled from fishery landings, and time and
location data were approximate. Samples came from all months and through
out the region, but sampling effort was not equally distributed and was
concentrated from May through September and in the middle of the region
(South Carolina and Georgia). In spite of some temporal and spatial sampling
limitations, we determined that several species such as small senanids,
haemulids, sparidsand lutjanids spawn over protracted periodsand throughout
the region. Other species such as Helicolenus dactylopterus, Caulolatilus
microps, Epinephelus niveates, Lopholatilus chamaeleonticeps, Hyperoglyphe
perciformis and Polyprion americanus have specific habitat requirements and
live and spawn in very restricted areas. Several species (Mycteroperca
microlepis, M. phenax) appear to spawn at specific shelf-edge reef sites (50 100 m depth), and tagging indicated they may undertake migrations to those
specific sites during the spawning season. Some of the shelf-edge sites are
utilized by several species, including some with moderately protracted
spawning seasonsthat peak duringwinter or summer months. These sites may
be in nearly continuous use by spawning fishes year-round, and should be
considered as no-take MPAs to protect spawning adults.
KEY WORDS: Essential Fish Habitat, Geographic Information Systems,
Marine Protected Areas
Page 464
Sitios de Desove de Peces de Arrecife en el
Atiintico Sudeste (USA)
Se determino la condici6n de desove de 28 especies de peces de
arrecife representando a 11 familias (Balistidae, Berycidae, Carangidae,
Centrolophidae, Haemulidae, Lutjanidae, Malacanthidae, Polyprionidae,
Scorpaenidae, Serranidae, Sparidae). Los especimenes se obtuvieron en las
aguas de las Carolinas, Georgia y de la costa este de la Florida (incluyendo los
Cayos) en profundidades de 16 a 686 m. La presencia de ovocitos con nucleo
migratorio, ovocitos hidratados y/o foliculos postovulatorios se utilizo para
acertar el desove inminente o muy reciente. Los sitios de captura de peces en
condition de desove fueron trazados usando Sistemas de Informacion
Geografica (SIG). El comportamiento reproductive de algunas especies fue
observado desde un sumergible. La mayoria de los especimenes fueron
obtenidos mediante muestreo independiente de la pesca, con el tiempo y el
sitio de los muestreos registrados exactamente. Algunosde los especimenes se
obtuvieron pormedio de la industria pesquera, y la hora y los datos del sitio de
captura son aproximados. Las muestrasprovinieron de todos los meses del arlo
y de toda la region, pero el esfuerzo del muestreo no se distribuyo iguaimente
sino que se concentro de mayo a octubre y en el centra de la region (Carolina
del Sur y Georgia). A pesar de los limites del muestreo, determinamos que
varias especies tales como serranids pequenos, haemulids, sparids y lutjanids
desovan durante periodos prolongados y por toda laregion. Otras especies tales
como Helicolenus dactylopterus, Caulolatilus microps, Epinephelus niveatus,
Lopholatilus chamaeleonticeps, Hyperoglyphe perciformis y Polyprion
americanus tienen requisites especificos del habitat y viven y desovan en areas
muy restringidas. Aparentemente varias especies (Mycteroperca microlepis,
M. phenax) desovan en sitios especificos de 50 a 100 m en el borde del
continente, y de acuerdo con estudios de marqueo, estas especies emprenden
migraciones a esos sitios especificos durante la estacidn dedesove. Algunos de
los sitios del borde del continente son utilizados por varias especies,
incluyendo algunas con estaciones de desove moderadamente prolongadas que
alcanzan su punto masalto durante los meses de inviemo o verano. Los peces
pueden utilizar estos sitios para el desove casi continuamente a lo largo del
ano, y por lo tanto estas areas se deben considerar como Areas de
Conservacion Marinas donde no se permite la captura de ninguna especie para
proteger el desove de peces adultos.
PALABRAS CLAVES: Areas de Conservacion Marinas, habitat esencial para
peces, Sistemas de Informacion Geograficos
Sedberry, G.R. et al.GCFI-.57 (2006)
Page 465
INTRODUCTION
In the re-authorization of the Magnuson-Stevens Fishery Conserva
tion and Management Act, through the Sustainable Fisheries Act, the U.S.
Congress included provisions that required fishery management councils to
identify essential fish habitat (EFH). Such EFH should include "those waters
and substrate necessary to fish for spawning, feeding or growth to matur
ity" (Schmitten 1999). The Magnuson Actre-authorization also provided for
recognition of Habitat Areas of Particular Concern (HAPC) for various fish
stocks or assemblages (e.g., Murawski et al. 2000). HAPC are areas where
some user activities (e.g., trawling, bottom longlining) are banned because of
particularly sensitive habitats or species assemblages such as ivory tree coral
(Oculina varicosa) and associated organisms (Reed 2000). In order to manage
fisheries under EFH and HAPC provisions, it is necessary to recognize and
map EFH and HAPC, and tomore clearly define them inrelation to the fishery
management unit (e.g., the Snapper-Grouper Complex of the U.S. South
Atlantic Fishery Management Council). Spawning grounds, by definition, are
EFH. Likewise, spawning areas must certainly qualify as HAPC, asspawning
habitats are important in the life history of fishes and, for reef fishes in
particular, often contain sensitive species assemblages such as corals and
sponges.
In tropical and warm-temperate zones, many reef fishes undergo migra
tions to spawn at particular reef sites that probably possess hydrographic
regimes or biological assemblages that enhance survival of offspring. Many
species of coral reef fish spawn inlarge aggregations, wherein large portions of
a dispersed population migrate to specific sites at specific times of the year to
spawn (Domeier and Colin 1997). Because of the physical and biological
conditions that are apparently favorable for survival of eggs and larvae, many
different species use the same sites on tropical coral reefs (e.g., Carter and
Perrine 1994). As a first step in mapping EFH and HAPC it is essential to
determine where fishes spawn, where fishes that aggregate to spawn gather in
spawning condition, and what sites are important spawning locations for
multiple species, so that these areas can be given further considerations for
management, such asarea closures, that protect spawning fish. Determination
of precise spawning times is essential for establishing time closures that might
protect spawners and enhance recruitment. For species with protracted
spawning periods, or for areas used as spawning grounds by many species that
spawn at different times of the year, permanent closure of the grounds may be
needed to protect spawning assemblages of fishes. Of greatest priority is
determining spawning grounds for exploited reef fishes, especially those that
are exploited during the spawning season when Uiey are aggregated at specific
locations and times. Off the southeastern United States, such priority species
and habitats include at least some of the 73 species of the Snapper-Grouper
Complex (e.g., snappers, groupers, porgies, grunts, tilefishes) that are managed
by the South Atlantic Fishery Management Council (SAFMC), and their hardbottom and sponge-coral habitats.
The South Carolina Department of Natural Resources (SCDNR) has
conducted research since 1973 on die continental shelf and slope off the
Page 466
southeastern U.S., in an area often referred to as the South Atlantic Bight
(SAB), from Cape Hatteras to Cape Canaveral. Some surveys have extended
south to the Florida Keys, and offshore to the Charleston Bump area of the
Blake Plateau. Through cooperative programs with federal resource manage
ment agencies, the SCDNR has conducted basic descriptive faunal surveys,
fishery assessment surveys, monitoring surveys, and studies directed atspecific
resource management problems. Surveys have includedsamplingof demersal
fishes with a variety of fishing gear; and hydrographic, benthic and ichthyoplankton sampling (e.g., Wenner 1983, Mathews andPashuk 1986, Collins and
Stender 1987, McGovem, Sedberry and Harris 1998, Harris et al. 2001).
Various cooperative state-federal projects at SCDNR have conducted detailed
life history studies of many reef fishes. These have included descriptions of
age and growth, reproduction, feeding habits, early life history, movements
determined by tagging, and population genetics (e.g., Collins and Stender
1987, Sedberry and Cuellar 1993, Van Sant et al. 1994, Sedberry et al. 1999,
McGovern et al. 1998). Ichthyoplankton (1973-1984), trawl (1973-1987) and
trap (1978-2004) surveys have included region-wide annual sampling cruises.
Studies of reproductive biology of reef fishes have included determination of
spawning times and frequencies (e.g., Cuellar et al. 1996). Tagging studies
have indicated movementsto locations suspected to be spawning grounds (Van
Santetal. 1994).
Data from the published studies cited above, from monitoring and
sampling that has continued since those publications, and a substantial
database on other species of the region are available for additional analyses.
Of particular interest in a re-analysis of the historical data is the goal of using
recently developed spatial and geographic analysis tools unavailable or not
considered when many of the original data analyses were performed. Spatial
analysis tools such as Geographic Information Systems (GIS) can be used on
these databases to determine areas that support greater abundance, biomass
and/or diversity of fishes. The databases can also be examined to describe
distribution of individual species in relation to bottom and hydrographic
features. Importantly, the databases can be queried for locations of fish in
spawning condition, locations where large numbers of juveniles are found
(recruitment areas) and locations where early larvae of priority species are
found (spawning areas). Mapping of EFH and HAPC for reef fishes off the
southeastern U.S. Atlantic coast is of particular importance at this time, as
increasing demands are placed on the resource (see Coleman et al. 2000 for
review). The consumption of fishes by humans has increased dramatically in
the last several decades because of increases in human population, per-capita
consumption of seafood, and advances in fishing technology. Reef fishes such
as those of the warm-temperate hard-bottom reefs in the SAB appear to be
particularly at risk, and many species are undergoing overfishing, are over
fished, or are in danger of being so (Coleman et al. 2000, NMFS 2004).
Severe restrictions, including size limits, bag limits, closed seasons and limited
entry have been imposed on a species-by-species basis by the SAFMC. More
restrictions might be needed; for example, die fishery for red porgy in the U.S.
Atlantic was closed in 1999 because of extremely low spawning potential. The
economic value of the reef species complex makes protectingthe sustainability
Sedberry, G.R. et al. GCFI:57 (2006)
Page 467
of the fishery a critical consideration for this region. Commercial reef fish
landings in the SAB from 1980-1996 were roughly 147 million lbs, with anexvessel value near $186 million (www.stnmfs.gov/stl/commercial/landings/
annual_landings.html).
Many economically important reef fish species share a suiteof life history
and behavioral characteristics that make them particularly susceptible to
overexploitation. These characteristics include long life, large adult size, late
maturity, protogyny, and spawning in aggregations or at sites that are predict
able in time and space (Coleman et al. 2000). Predictable spawning aggrega
tions are particularly well-documented in tropical reef fishes, and the negative
impacts of fishing these aggregations are well-known(Craig 1969, Carter et al.
1994, Domeier and Colin 1997, Sala et al. 2001). Althoughsome studies have
presented evidence for spawning aggregations of gag (Mycteroperca microlepis) on temperate reefs of the Gulf of Mexico (Coleman et al. 1996), it is
uncertain if such aggregations represent a majorregional spawning ground, as
has been documented for some tropical groupers (Carter et al. 1994), and what
the effects might be of fishing suchaggregations ifthey do represent the major
reproductive output for a large region. There are few data available on
spawning locations, times and behavior of reef fishes of the SAB, but there is
some circumstantial evidence for aggregations of some species such as gag.
Circumstantial evidence includes long-distance migrations that sometimes
coincide with the spawning season, and are thought to be movements toward
pre-spawning aggregations or movements to actual spawning sites(Van Santet
al. 1994, McGovem et al. in press). Additional circumstantial evidence for
spawning aggregations of gag inthe SAB includes capture offish in spawning
condition (presence of migratory-nucleus oocytes, hydrated oocytes or postovulatory follicles) at specific depths suchasdeep shelfedgereefs(MARMAP
unpublished data). Such capture might represent spawning aggregations that
should certainly be classified as EFH. If fishermen target these aggregations,
additional HAPC consideration should be given to current management plans,
so that such spawning sites can be protected during the spawnmg season. If
such spawning sites are used by many species for much of the year, additional
protection should be provided in the form of no-take MPAdesignation.
Spawning aggregations in reef fishes are believed to correspond spatially
and temporally withhydrographic features that insure greatest survival of early
lifehistory stages. For this reason, many species utilize the same locations for
spawning, often at different times of the year (e.g., Carter et al. 1994, Carter
and Perrine 1994). These hydrographic features are often associated with
prominent bottom features that influence circulation near (and downstream
from) the spawning banks(Carter et al. 1994, Sedberry et al. 2001,Govoni and
Hare 2001). Many reef fishes with pelagic eggs and larvae spawn in the
vicinity of gyres near the shelf edge (Johannes 1978). Such topographicallyproduced gyres are implicated in removal of pelagic eggs from the spawning
site, thus reducing predation, while retaining fish eggs and larvae for the
ultimate return of larvae to the shelf at later developmental stages that can
avoid some predation. Such gyres may carry eggs and larvae toward ideal
post-larval settlement habitat, or toward areas of high larval fish food produc
tion. Along the continental shelfedgeof the SAB, there are areas of gyres and
Page 468
upwelling that are associated with high nutrients and plankton productivity
(Paffenhoffer et al. 1984, Mathews and Pashuk 1986). Small occasional
frontal eddies and meanders that propagate northward along the western edge
of the Gulf Stream provide small-scale upwellings of nutrients along the shelf
break in the SAB (Miller 1994). Such intermittent upwellings might coincide
with reef fish spawning times and locations. In addition to these intermittent
upwellings, there are two more permanent upwelling areas in the SAB. One is
locatedjust to the north of Cape Canaveral and is caused by diverging isobaths
(Paffenhofer et al. 1984). The othermuch larger and strongerupwelling occurs
mainly between 32°N and 33°N (Atkinson 1985, Mathews and Pashuk 1986)
and results from a deflection of the Gulf Stream offshore by the topographic
irregularity known as the Charleston Bump (Bane et al. 2001). Off of South
Carolina and North Carolina, the large meanderset up by the Charleston Bump
forms the Charleston Gyre, an eddy with upwelled water at its core, and which
moves shoreward across the edge ofthe shelf and may be important in reef fish
recruitment.
The presence of high nutrients at the shelf edge, and a gyre mechanism to
transport larvae from shelf-edge spawning to estuarine nursery habitats
influences recruitment success in gag (Sedberry et al. 2001). Recruitment in
gag and some other fishes is correlated with the location, strength, and
persistence of the Charleston Gyre (Sedberry et al. 2001, Govoni and Hare
2001). It is likely that spawning of gag and other reef fishes off the Carolinas
is timed and located to take maximum advantage of the hydrographic condi
tions created by the Charleston Bump complex from 32°N and 33°30'N
(Sedberry et al. 2001, Govoni and Hare 2001). Other intermittent upwelling
sitesalong the shelf edge of the SAB, andthe morepermanent upwellingnorth
of Cape Canaveral might also be important spawning grounds. Life history
and spawning strategies of reef fishes might be timed to coincide with different
upwelling types, times and locations. For example, fishes that spawn in a few
large aggregations might utilize areas of more permanent gyres, while fishes
with protracted seasons (spawning many times) might use more intermittent
upwelling areas. Such areas might be considered EFH or HAPC, and it is
important to map prominent and persistent hydrographic features in relation to
distribution of fish larvae, juveniles and adults to determine the spatial
relationships among life historystages and hydrographic features.
As a result of overfishing and the apparent inability of traditional methods
to reverse declines in abundance of deep reef fishes, the SAFMC has proposed
a series of Marine Protected Areas (MPAs) that could include no-take marine
reserves (SAFMC 2004). The SAFMC has recently gone through an exercise
in siting MPAs that included obtaining input from user groups, interested
parties, and the general public, along with some review of existing biological
and habitat data. Of prime concern is protecting those spawning habitats and
locations that are essential to completing the life cycles of overfished species.
Also of concern is placement of MPA networks to maximize spawning
potential and recruitmentof larvae from protectedareas to harvest areas and to
other protectedareas in orderto provide fishing opportunitieswhile conserving
spawning stock biomass. Additional study of distribution of individual reef
fish species and spawning sites in relation to bottom habitats and faunas, and
Page 469
the relationship of bottom features to hydrographic features and proposed
MPA sites, is needed. These data are needed to maximize the effectiveness of
severe management measures, such as no-take reserves, that are perceived to
be an extreme burden on commercial and recreational reef fish fishermen. By
strategic placement of MPAs in networks based on biological and oceano-
graphic data, it is hoped that themaximum positive effect canbe achieved with
the minimum impact on fishermen. It is imperative to collect and summarize
such biological and oceanographic data, particularly data on spawning
locations and recruitment pathways.
We have utilized a 30-year fishery-independent database to build a GIS
that has mapped distributions of species, and their abundance, biomass and
diversity. We have also mapped data on gonad condition for several fishery
species using this database and some fishery-dependent sampling. In this
paperwe will describe some of the results aimedat locatingspawning grounds
for reef fishes. We hypothesizethat species that appear to form large aggrega
tionsdo so at specific sites and times that are relatedto cyclicalyet permanent
hydrographic features. We also hypothesize that species that appear to have
protracted spawning in small widely-distributed groups may use ephemeral
features such as those that form intermittently during summer and fall. The
purpose of this paper is to report on the results of a temporal and spatial
analysis of the data available on reproduction in several speciesof reef fish, in
order to determine locations of EFH and HAPC for spawning reef fishes, and
sensitive areas that might need intensive management in the form of temporal,
spatial or some combination of no-take Marine Protected Areas(MPAs).
METHODS
Study Area, Field Methods and Databases
The MARMAP (Marine Resources Monitoring, Assessment and Predic
tion) fishery-independent database that went into this analysis consisted of a
variety of demersal fish surveys conducted from several research vessels
(Figure 1, Table 1). Details of sampling can be obtained from the senior
author. Briefly, fish surveys generally covered the region from Cape Fear,
North Carolina to Cape Canaveral, Florida, with some stations outside that
range. Surveys were conducted withbottom trawls (e.g., Wenneret al. 1979,
Wenner 1983), baited fish traps (Collins 1990), bottom longlines and hookand-line (Harris et al. 2004). MARMAP trawling was conducted from 1973 to
1987, in depths from 9 - 366 m. Trawl stations were established randomly
within depth and latitude strata; along transects perpendicular to the coast; or at
index monitoring sites in reef habitat. Those index stations were also sampled
with fish traps from 1978 to the present; however, since 1987 the trap survey
has been conducted at randomly chosen reef points (e.g., McGovern, Sedberry
and Harris 1998), many of which are at or near the trap index stations sampled
from 1978 - 1986.
Page 470
raw
nvt
WW
Figure 1. Sampling locations, by fishery-independent gear type, for specimens
used inthe spatial and temporal analysis ofreeffish spawning.
Table 1. Summary of primary sampling gear used in collection of specimens; and months, years, latitude and depths of collections. Ind •
fishery-independent samples; Dep =fishery-dependent samples.
Gear
Conductivity-ternperature-Depth
(CTD)cast
Blackfish trap
Chevron fish trap
Florida snapper trap
Mini-Antillean S-trap
Number of
Month
Year
Latitude
Depth (m)
Collections
Range
Range
Range (°N)
Range
Ind
De
1987-2003
1977-1999
1987-2003
1980-1989
1977-1980
27.2-34.6
30.7-34.3
27.2-34.6
30.4-34.3
30.7-33.7
15-789
X
X
1982-2003
1982-1986
1979-2003
27.9-38.7
32.0-32.8
28.2-34.2
15-500
44-229
1983-2003
1974-2003
1989-2003
1986-1989
26.0-34.4
18.2-34.7
3298
6185
Mar-Oct
Jan-Dec
Mar-Dec
1710
Feb-Sep
1393
157
Jan-Feb
15-65
13-218
15-196
19-75
X
X
X
X
X
X
May-Sep
Bottom bngOne
KaO pole bottom tongline
Vertical bngOne
502
199
May-Sep
305
Feb - Mar
Hook and line (rod &reel)
Snapper reel
389
3226
Jan-Dec
X
X
X
X
X
X
X
X
25.8-32.0
29.1-33.9
1-234
11-256
396-838
3-13
X
X
X
X
1980-1987
31.6-34.3
15-35
X
X
28.7-34.9
28.7-40.6
26.0-32.5
4-20
9-686
17-52
X
X
X
49-220
X
May-Sep
Jan-Dec
Jan-Dec
Jan-Dec
Falcon net (23-m otter trawl)
452
232
Fly net (16-m bottom trawl)
145
Feb
1071
1214
Jan-Dec
Jan-Dec
1980-1987
1973-2001
38
Feb-Aug
1988-2002
Wreckfish reel
Apr
Aug - Oct
Apr-Sep
Otter trawl (18-m semi-balloon)
Yankee trawl (3/4 scale)
Spear gun
Oct,Dec
X
Page 472
In order to sample deeper habitats, we employed experimental longline
gear, directed at two habitat types: upper continental slope reefs(100 - 250 m)
and mud-bottom tilefish grounds(175 - 225 m).
Data collected from each sampling gear included location, hydrographic
parameters (measured with CTD), species composition, abundance, biomass,
and length frequency of all fish species caught. Stations were located using
LORAN-A, LORAN-C, or GPS, and the best available navigation technology
was used at the time of fishery-independent sampling. All fish samples from
fishery-independent sampling that were processed for reproductive studies
wereobtained using LORAN-C ordifferential GPSnavigation.
Subsamples of certain priority species in the catches (Table 2) were
dissected to obtain otoliths and gonad tissues. For those fishes, all appropriate
lengths and weights were measured and the otoliths and gonads removed.
Gonads were fixed in the field in 10% seawater formalin solution.
In addition to samples collected during the fishery-independent surveys,
we sampled commercial catches to obtain a full size range of specimens or to
obtam samples outside of the months (generally May through September) mat
fishery-independent sampling occurred. Samples were processed in the field
and lab in the same manner as those collected during fishery-independent
surveys; however, precise catch time and location were not always available.
Catch location was often reported as a National Marine Fisheries Service
(NMFS) Reef Fish Logbook statistical grid cell number. Those cells are one
degree of latitude by one degree of longitude or about 10,440 km2 for this
region. Deficiencies in time andlocation data werenoted in the data analysis.
Laboratory Processing of Gonad Samples
Reproductive tissues were vacuum infiltrated andblocked in paraffin, and
then sectioned(7 mm thickness) on a rotary microtome. Three sections from
each sample were placed on a glass slide, stained with double-strength Gill's
hematoxylin and counter-stainedwith eosin Y. Sections were viewed under a
compound microscope at 40 - 400X and for most species two readers inde
pendently assigned sex and reproductive state with criteria from Harris et al.
(2004) for gonochorists and from Wenner et al. (1986), Harris and McGovem
(1997) and McGovem et al. (1998) for hermaphrodites. Date of capture,
specimen length, and specimen age were unknown to the readers. If the
assessments differed, both readers viewed the slide simultaneously and
agreement was reached. Spawning females of all species had at least one of
the following structures in histological sections:
i) Migratory-nucleus oocytes,
ii) Hydrated oocytes, or
iii) Postovulatory follicles.
Page 473
Table 2. Species on which SCDNR has collected life history samples from
which dataon sexand reproductive statewere obtained for spatial and
temporal analysis.
Family
Scientific Name
Berycidae
Beryxdecadactylus
Scorpaerridae
Helicolenus dactytopterus
Potyprionidae
Polyprion americanus
Common Name
red bream
blackbeOy rosefish
wreckfish
Serranidae
Centropristisocyurus
Centropristis striata
Cephalopholis cruentata
Cephalopholis fulva
Diplectrum formosum
Epinephelus adscensionis
Epinephelus drummondhayi
Epinephelus flavolimbatus
Epinephelus mono
Epinephelus nigritus
Epinephelus nh/eatus
Mycteroperca interstitialis
Mycteroperca microlepis
Mycteroperca phenax
bank sea bass
black sea bass
graysby
coney
sand perch
rocklirtd
speckled hind
yellowedge grouper
redgrouper
warsaw grouper
snowy grouper
yellowmouth grouper
gag
scamp
Malacanthidae
Caulolatilus microps
Lopholatilus chamaeleonticeps
Carangidae
Seriola dumerili
blueline tilefish
tJlefish
greateramberjack
Lutjaridae
Lutjanus campechanus
Rhomboplites aurorubens
Haemulidae
Haemulon aurolineatum
Haemulon plumieri
Sparidae
Calamus nodosus
Pagruspagrvs
Centralophidae
Hyperoglyphe perciformis
red snapper
vermilion snapper
tomtate
white grunt
knobbed porgy
redporgy
barrelfish
Balistidae
Batistescapriscus
gray triggerfish
Page 474
Data Manipulation, Standardization and GIS Analysis
Data from the surveys (fishery-independent and -dependent) and labora
tory analysis were incorporated into a database that could be queried for
speciesidentification, collection data, sex and reproductive state. The database
also included hydrographic measurements taken by CTD deployed at the same
time as the fish collections (+ 2 h), and within one kilometer of the fish
collection sites. We queried the database for the priority species for which we
had reproductive data (Table 2) and exported the data to ESRI Arclnfo
ArcMap 9.0 for spatial analysis. We plotted location of capture of all speci
mens of each species, and overlaid location of capture of spawning females (as
defined above) on the same map. Where relevant, we included on each map
the location of proposed no-take (no bottom fishing) MPAs that are currently
under consideration by the SAFMC (SAFMC 2004). We also analyzed
occurrence of spawning females by month to define spawning season and
temporal peaks in spawning activity. We calculated mean (± one standard
deviation) and range of bottom temperatures recorded when spawning females
of each species were collected. Data reported in tables were from fisheryindependent sampling only, and depth, location, time and temperature data are
accurate. Maps generated from the GIS analysis included approximate
locations from some fishery-dependent samples, and those are differentiatedon
the maps.
Fishery-independent sampling effort was not equally distributed, either
spatially or temporally (Figure 1, Table 1), and was concentrated from May
through September and in the middle of the region (South Carolina and
Georgia). Fishery-dependent samples provided accurate temporal information
(+ 5 days) on spawning times for those months not sampled during fisheryindependent surveys, but location data, particularly those collected by NMFS,
were often "rounded" to the nearest degree of latitude and longitude.
In spite of some temporal and spatial sampling limitations, we found that
fish species examined exhibited a variety of spatial patterns of spawning
activity, with respect to their general distribution, habitat features and in
relation to other species. Several species such as small serranids, haemulids,
sparids and lutjanids spawned over protracted periods and throughout the
region (Table 3).
Black sea bass (C. striata), a small serranid, were distributed across the
continental shelf throughout the region, generally in depths less than 60 m
(range: 2-130 m). Of 30,170 examined to determine sex and reproductive
state, 2251 were spawning females (Table 3). Spawning sites were located
throughout the region in depths of 15 - 56 m (Figure 2), although most were
found mainly in the middle of the SAB. Spawning females were collected
during most months of the year (Table 4), with a major spawning period of
February through April. In contrast, black sea bass north of Cape Hatteras
spawn mainly from June through September (Able et al. 1995); however,
spawning times here were similar to those found in the Gulf of Mexico
Page 475
Pecember to April (Hood et al. 1994)]. Bottom water temperatures where
spawning females were collected ranged from 11.45 to 26.57°C (Table 3, N =
898 independent measurements).
Figure 2. Locations of capture of black sea bass, including all captures and
capture of spawning females, by survey type (fishery-independent vs. fisherydependent). Sites proposed as MPAs that would prohibit bottom fishing are
X
also shown.
\
Table 3. Collection data for species examined for spawning activity. Data include total number of specimens collected, numbb.
examined to determine sex and reproductive state, and number found to be spawning females; depth of capture of all specimens and of
spawning females; latitude range (°N) of collections of spawning females; and bottom temperatures (mean, standard deviation and range)
where spawning females were collected. Depth, latitude, and temperature data were from fishery-independent sampling. In some cases
(-), data were not available.
Capture
Total Soecimens
Species
B. capriscus
B. decadactylus
Collected
Death
Exam Spawning (m) (m)
Spawning
Depth
(°N)
Spawning
Mean
7582
4349
141
C.microps
C.ocyunjs
17
3210
1344
20754
16
1181
1112
2402
8
88
514
52
21-155
46-256
1-146
45-60
48-234
27-57
31-32
32-32
32-32
C. striata
C. ctuentata
118059
11
30170
7
2251
0
2-130
30-50
15-56
27-34
24
18
12830
43
780
34
274
73
1
634
5
39-58
9-84
33-83
39
17-47
37-53
5
28-114
31-205
22-95
C. nodosus
C.futva
D. foimosum
E.adscensionis
£ drummondhayi
E. RavoSimbatus
E.morio
C
«*n*ir»»lr) •*»
427
1000
2390
2223
•lO
6
46
4
13-128
-
JO
20-75
-
4CO
-
-
160-194
30-90
4CO
Spawning
Temperatures (°C)
Latitude
27-33
-
-
33
27-34
32-32
32-32
32-32
32-34
Range
sd
22.41
-
1.96
-
18.87-27.42
-
21.92
0.68
20.10-22.67
14.91
16.81
18.88
2.12
0.63
8.87-16.28
16.24-18.63
2.68
11.45-26.57
-
23.80
23.55
21.75
-
14.47
21.01
-
-
3.09
1.51
-
-
2.09
-
23.80-23.80
14.03-28.50
20.05-23.96
-
14.47-14.47
16.97-24.08
iable 3. Continued.
Capture
Total Specimens
Species
H. dacfytopte/us
H.peKJfonni$
Lc/iamae/eo/ificeps
Lcampec/iant/s
M inlersifflalis
Collected
Eixam
Death
Spawning (m) (m)
Spawning
Depth
m
Spawning
Spawning
Latitude
Mean
32-32
Temperatures l'C)
Range
sd
229-238
12
324
38-686
181-520
62-311
190-300
31-32
13.02
1.96
10.16-14.90
778
18
80
9
7-240
27-84
24-67
27-33
32-32
23.16
2.02
18.05-27.59
17.26
21.18
1.84
17.26-17.26
15.60-24.08
16.88
0.89
16.24-18.99
4280
1381
138
353
3552
102
2431
1225
29
-
49-51
.
.
.
-
-
-
-
-
-
Mm/c/ofep/s
M.p/ienax
P.pag/us
7329
3759
5363
2467
1848
351
15-117
17-113
24-117
33-93
26-33
29-32
22732
15687
457
9-307
26-57
30-32
P. amencanus
Rau/o/utens
2067
41455
1466
11798
55
3280
44-653
14-163
433-595
18-97
31-31
27-34
23.37
2.01
16.01-28.09
2797
2498
250
15-216
45-122
24-33
23.71
0.00
23.71-23.71
S. di/me/r//
-
-
•
-
\
Tablo 4. Spawning periods for fishes examined. Spawning percentage = percent of female specimens in spawning condition.
Dark gray indicates major spawning period. Light gray indicates months of spawning activity.
Spades
B. capiiscus
B. docadactytus
n
Female*
2259
11
Spawning
Percentage
11.70
C. mlcrops
619
63.04
1267
19740
4.10
11.40
C. cruontata
4
0.00
C. futva
8
12.50
D. formosum
E. adscensionis
E. drummondhayi
E. flavolimbatus
E. morio
E.nigritus
779
81.39
12
41.67
169
2.96
0.0
0.0
52
11.54
0.0
0.0
2058
2.24
9
11.11
E. nlveatus
533
18.01
H. aurollneatum
925
25.73
H. ptumleri
H. dactyloptems
H. perciformis
L. chamaeleonticeps
L. campochanus
1227
12.31
548
25.18
68
17.65
1101
27.91
402
19.90
12
75.00
M. mlcrolopls
4872
37.93
M. phenax
1988
17.66
M. Interstltlalis
P. pogrus
Nov.
72.73
752
C. striata
Jun.
6.24
C. nodosus
C. ocyurvs
Porcontaoe In spawning condition bv month
Feb.
10870
4.20
P. americanus
793
6.94
R. ourorubons
8666
37.85
S. dumerili
1363
18.34
0.0
I 400JT>':\.--»:lK •
0.0
lu,-.a.5iC
0.0
•1 f*.JL
•••—^ ,V
* -• *• •••.v.v
. , j
saj-j.;
0.0
0.0
0.0
0.0
Page 479
Bank sea bass (C. ocyurus) were also broadly distributed across the shelf
throughout the region (Figure 3), but appeared to prefer deeper waters than
black seabass (range 1 - 146 m). Of 2402 examined for sex and reproductive
state, only52 were spawning females, and all of those were collected in depths
of 27-57 m off South Carolina in October through May (Tables 3-4). The
major spawning period was February through April. Spawning females were
collected in water temperatures thatranged from 16.24 to 18.63°C (n = 21).
Sand perch (D. formosum) were also widely distributed across the shelf
(Figure 4), generally in depths less than 60m (range 9-84 m). The sand perch
appears to be much less dependent onreefhabitat, and was oftentaken in trawl
collections over sandy bottom (e.g., Wenner et al. 1979, Darcy 1985). More
than 80% of the female sand perch examined were in spawning condition.
Spawning females (n = 634) were collected throughout the region from May
through September at depths of 17 - 47 m (Tables 3-4). Bottom temperatures
atspawning sites ranged from 14.03 to 28.50°C (n = 596). A similar spawning
season (April-October) wasreported from the southern Caribbean (Obando and
Leon 1989) and Bortone (1971) reported peak ovary maturation in May in the
northern Gulf of Mexico.
Like sand perch, tomtate (H. aurolineatem) were found across the shelf
throughout the region. Spawning females (n = 238 of 2412 examined)
occurred on middle and outer-shelf reefs (Figure 5) and were collected from
May through July in depths from 15-54 m (Tables 3-4). Bottom temperatures
at spawning sites ranged from 20.16 to 28.04°C (n = 232).
Red snapper (L. campeckanus) were also widely distributed across the
shelf (Figure 6, Table 3), but appeared to spawn at mid- to outer-shelfdepths
(24 - 67 m). Of 778 red snapperexamined for sex and reproductive state, 80
were spawning females. Spawning females were collectedin January and May
through October in the waters off South Carolina to Florida (Table 4). The
major spawning period was June through September. Red snapper spawned at
temperatures ranging from 18.05 to 27.59°C (Table 3; n = 41). Red snapper
were reported to spawn in the northeastern Gulf of Mexico from April through
October (Collins et al. 2001).
Vermilion snapper (R. aurorubens) were ubiquitous in collections on the
middle and outer shelf, and were found in depths from 14 - 163 m (Figure 7,
Table 3). Spawning females (n = 3280 of 11,798 fish examined) were found at
nearly all depths and latitudes where vermilion snapper occurred. Vermilion
snapper spawned in depths from 18to 97 m and at temperatures from 16.01 to
28.09°C (n = 2511). Spawning occurred from April through September, with a
major spawning period of May through September (Table 4). Spawning
appears to be slightly more protracted than in the Gulf of Mexico [May to
September (Hood and Johnson 1999)].
^>
Page 480
Figure 3. Locations of capture of bank sea bass. See Figure 2 for additional
explanation.
«
e
o
'S
•a
co
CM
£
co
a.
0
=
lS
TO CO
N.SS
N.K
U. Qj
Page 482
TTN
Figure 5. Locations of capture of tomtate. See Figure 2 for additional explana
tion.
Page 483
Figure 6. Locations of capture of red snapper. See Figure 2 for additional
explanation
Page 484
WW
Figure 7. Locations of capture of vermilion snapper. See Figure 2 for additionalexplanation.
Several species (Mycteroperca microlepis, M.phenax, Balistes capriscus,
Calamus nodosus, Pagruspagrus and Seriola dumerili) appeared to spawn at
specific shelf-edge reef sites (50 - 100 m depth) in spite of being generally
distributed across the shelf. Gag (M. microlepis) were caught throughout the
region (15 - 117 m) during fishery-independent sampling (Table 3, Figure 8).
Sedberry, G.R. etal. GCFL57 (2006)
Page 485
Because gag are winter-early spring spawners (from December through May),
few were collected during research cruises that sampled mainly from May
through September. However, fishery-dependent sampling yielded many
female gag in spawning condition from throughout the region. Of 5,363 gag
obtained from all sampling, 1,848 were spawning females. Most fisherydependent samples were landed under an emergency rule that required
fishermen to land gag with the gonads intact so that researchers could deter
mine sex ratios and other aspects of reproduction (McGovem et al. 1998).
Unfortunately, the emergency rule did not require accurate location data and
catch locationswere often reported in NMFS sampling grid cells (Figure 8). In
spite of the inaccuracy in location, it appears that gag spawn at shelf-edge
reefs, in depths from 24 -117 m, primarily from February through April (Table
4), at a bottom temperature of 17.26°C (only one measurement). Gag in the
Gulf of Mexico spawn slightly earlier than we found here [December to May,
with peak activity occurring during February and March (Hood and Schlieder
1992)].
Scamp (M. phenax) were found mainly on middle- and outer-shelf reefs
throughout the region (Table 3, Figure 9). Spawning females (n = 351 of2,467
examined) were found at shelf-edge reefs from northern Florida to South
Carolina from February to August (Table 4), with a major spawning period of
March through May. In the Gulf of Mexico, scamp spawning peaks from late
February to early June (Coleman et al. 1996). Spawning females were
collected at depths of 33 - 93 m and water temperatures from 15.60 - 24.08°C
(Table 3; n = 131). We observed scamp engaged in courtship behavior like
that described by Gilmore and Jones (1992) at shelf-edge reefs off northern
Florida and South Carolina in summer of 2002 and 2004 (off St. Augustine, 28
July 2002, 29.9°N, 80.3°W, 60 - 61 m depth, 1000 EDT, 19.46 - 19.49°C; off
St. Augustine, 29 August 2004, 30.0°N,80.3°W, 59 m, 0912 EDT, 17.8°C; off
Jacksonville, 30 July 2002, 30.4°N, 80.2°W, 56 - 85 m depth, 1923 - 1929
EDT, 20.90 - 20.94°C; ESE of Charleston, 1 August 2002,32.3°N, 79.0°W, 56
- 61 m depth, 1818-1829 EDT, 20.47 - 22.03°C). These observations involved
one gray-head (apparent) male scamp and one to a few apparent females.
Courtship behavior was observed, but not any spawning. As described by
Gilmore and Jones (1992), scamp occurred in various color phases; individual
fish were constantly in motion, and changed rapidly between different color
morphs. Apparent females (usually one or two, but up to five, courted by
single apparent males) tended to remain in the "brown phase", whereas the
apparent males switched between "gray-head" phase when pursuing females,
and "cat's paw" phase when turning away from apparent females. These
behaviors were observed in the morning and late afternoon. Spawning was not
observed, but as in other groupers (Carter et al. 1994) that may occur after
sunset (Harris et al. 2002), when we were not making observations. Bottom
temperatures during our observations were similar to those observed by
Gilmore and Jones (1992) during spawning activity in scamp.
Page 486
.?
Figure 8. Locations of capture of gag. See Figure 2 for additional explanation.
Note that all spawning locations deeper than 175 m are from fishery-dependent
collections, reported from NMFS statistical areas (see Methods).
7TW
Page 487
WW
Figure 9. Locations of capture of scamp. See Figure 2 for additional explana
tion.
Page 488
Greater amberjack (S. dumerili) occurred on middle- and outer-shelf and
upper-slope reefs throughout the region and were captured at depths of 15 216 m (Table 3; Figure 10). We examined 2,498 gonads, 250 of which were
from spawning females. Spawning females were collected from depths of 45
to 122 m. Only two spawning specimens were obtained from research cruises,
and they were collected at a water temperatureof 23.71°C. Spawning females
were collected from January through June, with a major spawning period in
April and May (Table 4). Most (88%) spawning greater amberjack were
collected by commercial fishermen in the Florida Keys during a special effort
aimed at obtaining gonads for determining fecundity, sex ratios and spawning
season. Most (95%) spawning females were collected from waters south of
30°N latitude, although there is evidence for spawning off the Carolinas and
Georgia too.
Knobbed porgy (C. nodosus) were more restricted to mid- and outer-shelf
reefs off the Carolinasand Georgia(21 - 155m, Figure 11). Spawningfemales
were found almost exclusively at outer-shelf reefs and occurred at depths of 45
to 60 m (Table 3). Of 1181 specimens examined for sex and reproductive
state, 88 were spawning females (Table 3). Knobbed porgy spawned over a
narrow temperature range (49 measurements; range = 20.10 - 22.67°C).
Spawning occurred from February through July, with a major spawning period
of April through May (Table 4).
Red porgy (P. pagrus) were also distributed across the middle and outer
shelf throughout the region, and spawning females were collected in depths
from 26 - 57 m (Table 3, Figure 12). Of 15,687 examined for sex and
reproductive state, 457 were spawning females. Females in spawning condi
tion were found from September through May at bottomtemperatures of 16.24
to 18.99°C (n = 18); however, the major spawning period was November
through March (Table 4). In the Gulf of Mexico, red porgy spawn from
January to April (Hood and Johnson 2000).
Gray triggerfish (B. capriscus) were broadly distributed across the
shelf (13 -128 m) throughout the region(Figure 13),but appear to concentrate
spawningon middle-shelfto shelf-edge reefs (20 - 75 m). Of 4,349 examined
for sex and reproductive state, 141 gray triggerfish were spawning females
(Table 3). Gray triggerfish and other balistids construct nests by moving
debris and fanning sediments on the bottom, creating a shallow cleared
depression. These nests are guarded by either parent for 24 - 48 hours after
spawning (Fricke 1980, Lobel and Johannes 1980). On 4 August 2002 (32.8°
N, 78.3°W; 54 m; 20.58°C) we observed a large (~30 cm TL) gray triggerfish
hoveringover a cleared depression about 75 cm in diameter. An apparent egg
mass could be observed in the bottom of the depression. Gray triggerfish
spawned from May through August, with a major spawning period of June and
July (Table 4), at temperatures of 18.87 - 27.42°C (N = 148; Tables 3. Gray
triggerfish also spawn in warmer months(peak in November and December) in
the southeastern North Atlantic [Ghana (Ofori-Danson 1990)].
Page 489
Figure 10. Locations of capture of greater amberjack. See Figure 2 for
additional explanation. Note that some fishery-dependent collections in south
Florida are as reported from NMFSstatistical areas (see Methods).
Page 490
•
•
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Rgure 11. Locations of capture of knobbed porgy. See Figure 2 for additional
explanation.
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Page 491
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Figure 12.
explanation.
Locations of capture of red porgy. See Figure 2 for additional
Page 492
env
79"W
78W
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Figure 13. Locations of capture of gray triggerfish. See Figure 2 for additional
explanation.
Sedberry, G.R. et al. GCFL57 (2006)
Page 493
White grunt (H. plumieri) and red grouper (E. morio) haddistributions that
differed from most shelfspecies (Figures 14- 15). Both species were caught
on Oie middle and outer shelf, mainly in the northern part of the SAB, and
apparently have a disjunct distribution (Zatcoffet al. 2004, Chapman et al. in
prep.). They are abundant in the Caribbean and southern Florida, butare not
common off northern Florida or Georgia. They appear to be more tropical
species that are found only in the waters of the northern SAB, which areunder
the influence ofthe CharlestonGyre (see additionaldiscussionbelow).
Of the 2,256 white grunt examined, 151 were spawningfemales. Spawn
ing females were collected from March through September at most locations
where white grunt occurred, with a major spawning period of April through
June (Table 4). Spawning occurred in depths from 22 to 51 m (Table 3).
White grunt spawned in warmer waters (20.23 - 27.42°C; n = 123) than other
species examined, reflecting its preference for warmerwaters.
Red grouper (E. morio) have a distribution similar to that of white grunt,
although spawning is generally restricted to depths greater than 40 m (Figure
15). Spawning females (n = 46) represented 2.1% of the 2223 red grouper
examined for sex and reproductive state (Table 3). Red grouperspawn in late
winter and spring (February through June with a peak in April; Table 4) in
depths from 30to 90 m. In the Gulf of Mexico, peak spawning occurs in April
(Coleman et al. 1996). Red grouper spawned in generally cooler waters than
white grunt (range 16.97 - 24.08°C; n = 7).
Several species such as Caulolatilus microps, Lopholatilus chamaeleon
ticeps, Epinephelus flavolimbates, E. niveates, Helicolenus dactylopterus,
Polyprion americanus, Hyperoglypheperciformis and Beryx decadactylus have
specific habitat requirements and were therefore collected and found in
spawning condition in very restricted areas. They generally exhibited pro
tracted spawning periods. Blueline tilefish (C. microps) were collected only
off of South Carolina on shelf-edge and upper slope reefs between 46 and 256
m (Figure 16). Blueline tilefish (n = 1112 examined for sex and reproductive
state) were found associated with hard bottom that occurs in that area
(Sedberry et al. 2004). Females in spawning condition (n = 514) were
collected from February through October, with a major spawning period of
March through September (Table 4). Spawning females were collected at a
temperature range of 8.87 - 16.28°C (n = 32).
Tilefish (L. chamaeleonticeps) also had a restricted depth and latitude
range (Table 3, Figure 17); however, tilefish are found on soft-bottom habitat
on the upper slope, where they construct burrows (Harris et al. 2001). Most
tilefish were collected off South Carolina and Georgia, and spawning females
were found in those areas. Spawning females ( 324 of 2431 fish examined)
were collected in all months except October and December (Table 4), in depths
from 190 to 300 m, at temperatures from 10.16 to 14.90°C (n = 9). The major
spawning period was March through July. North of Cape Hatteras, most
tilefish spawn from May to September(Grimes et al. 1988).
Page 494
Figure 14. Locations of capture of white grunt. See Figure 2 for additional
explanation.
WW
Page 495
WW
Figure 15. Locations of capture of red grouper. See Figure 2 for additional
explanation.
Page 496
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Figure 16. Locations of capture of blueline tilefish. See Figure 2 for additional
explanation.
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Page 497
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Figure 17. Locations of capture of tilefish. See Figure 2 for additional explana
tion.
Page 498
Yellowedge grouper (E. flavolimbatus), like blueline tilefish, had a
restricted depth distribution (Figure 18) and were also found mainly on shelfedge and upper-slope reefs off of the Carolinas at depths of 31 to 205 m.
Spawning females (six of 73 fish examined) were collected in August and
September in depths from 160 to 194 m, at a temperature of 14.47°C (one
measurement) (Tables 3-4). Yellowedge grouperspawn earlier (April to July)
in the southernCaribbean (Manickchand-Heileman and Phillip2000).
Snowy grouper(E. niveates) were collected on shelf-edge and upper-slope
reefs, mainly off the Carolinas (Figure 19). Spawning females (96 of 649 fish
examined)were collected from April through September, in depths from 187to
302 m (Tables 3 - 4). The major spawning period was May through August.
No bottom temperature data were available for collections of spawning snowy
grouper. During a submersible dive on snowy grouper habitat in August
(2002) off South Carolina, a bottom temperature of 13.27°C was measured,
although no spawning snowy grouper were observed during that dive
(Sedberry et al. 2004).
Blackbelly rosefish (H. dactylopterus) were also found over a relatively
restricted depth range over hard bottom, and were often caught along with
snowy grouper (Figure 20). Blackbelly rosefish were collected between 38 and
686 m and spawning females were caught in depths from 229 to 238 m (Table
3). Of 1,381 specimens examined, 138were spawning females. Femaleswere
in spawning condition from December through April, with a major spawning
period of January through April (Table 4). In the western Mediterranean Sea,
blackbelly rosefish spawn in January and February (Munoz et al. 1999). No
bottom temperature data were available for collections of spawning blackbelly
rosefish, and only one collection off South Carolina had location data (Figure
20).
Wreckfish (P. americanus) occurred only on the continental slope, on a
feature known as the Charleston Bump (Sedberry et al. 2001). Of 1,466
wreckfish examined for sex and reproductive state, 55 were spawning females.
Wreckfish were caught in depths from 44 to 653 m, and spawning females
were caught in depths from 433 to 595 m (Table 3, Figure 20). Wreckfish on
the Charleston Bump have been collected at temperatures ranging from 6.2 to
16.3°C (Sedberry et al. 1999), and observed from submersibles (September
2001; August-September 2003) at temperatures of 8.4 - 16.7°C in depths from
430 to 570 m. Females in spawning condition were collected from November
to May and were most prevalent in samples from February and March (Table
4). The Charleston Bump is the only known spawning area for wreckfish in
the western North Atlantic (Sedberry et al. 1999); wreckfish in the South
Atlantic (Brazil) spawn in the austral winter [July to October (Peres and
Klippel 2003)].
We obtained 325 barrelfish (H. perciformis) from commercial fishermen
and conducted histological examination of 102 specimens. All samples,
including spawning females, came from wreckfish fishermen fishing on the
Charleston Bump (Sedberry et al. 2001). The distribution of adult barrelfish is
similar to that of adult wreckfish and spawning locations and times are about
the same. Of the 102 specimens examined, 12 were females in spawning
condition (Table 3). Females in spawning condition were found from Novem-
Page 499
ber through January and in May (Table 4).
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Figure 18. Locations of capture of yellowedge grouper. See Figure 2 for
additional explanation.
Page 500
Figure 19. Locations of capture of snowy grouper. See Figure 2 for additional
explanation.
erw
81 "W
Page 501
WW
8TW
Figure 20. Locations of capture of blackbelly rosefish and wreckfish. See
Figure 2 for additional explanation.
Page 502
Red bream (B. decadactylus), like wreckfish and barrelfish, were collected
by commercial wreckfish fishermen fishing on the Charleston Bump (Sedberry
2001). Of 16 specimens examined, eight were spawnmg females collected in
June through September (Table 4). No spawning females were present in
samples from April, May, November and December. No depth or temperature
data were obtained from the commercial fishermen, but location and tempera
tures were similar to wreckfish catch locations.
Three additional species of grouper were also rarely collected in spawning
condition. Yellowmouth grouper (M. interstitialis) was occasionally taken at
middle- and outer-shelf reefs off of South Carolina (n = 18), where a few
females (n = 9) were found in spawning condition in February, March and
August off South Carolina at depths of 49 - 51 m (Tables 3-4, Figure 21).
Only one bottom temperature was recorded at one spawning location (14.47°
C). Rock hind (E. adscensionis) were collected mainly at shelf-edge reefs off
of South Carolina and, of 34 examined for sex and reproductive state, five
were spawning females collected during March, May and June from depths of
37 - 53 m (Tables 3-4, Figure 21). Bottom water temperatures for those
collections were 20.05 - 23.96°C (n = 6). Speckled hind (E. drummondhayi)
were distributed throughout the region on outer-shelf to upper-slope reefs in
depths from 28 to 114 m, and were collected more frequently (274 examined)
thanrock hind (Table 3, Figure 22). Five spawning females were found off of
South Carolina in May, June and September(Table 4).
In addition to the above species of grouper, we also examined gonads of
seven graysby (C. cruentata), 18 coney (Cfulva) and 12 warsaw grouper (E.
nigritus) collected throughout the region (Table 3). Several of the warsaw
grouper were collected in proposed MPA sites off northern Florida and South
Carolina. One spawning female was caught in May on the upper slope at a
depth of 168 m (location unknown). An additional warsaw grouper examined
from the database contained late vitellogenic oocytes, perhaps indicating
potential spawning in the region. We collected one female coneyin spawning
condition in June (33.8°N, 76.8°N, 39 m), and one potential spawner in the
same month with late vitellogenic oocytes. In Puerto Rico, coney spawn from
December to March (Jimenez and Fernandez 2001). One female graysby
examined also contained late vitellogenic oocytes, again perhaps indicating
potential spawning in the region. We observed several running ripe male
coney and graysby; however, male reef fishes are in spawning condition for
much of the year and cannot be used to determine spawning location in the
absence of females. In addition to the histological evidence of spawning cited
above, we have observed courtship behavior in hogfish, Lachnolaimus
maximus, at shelf-edge reef sites. Hogfish courtship was observed from
submersible off Jacksonville, Florida on 30 July 2002 (30.4°N, 80.2°W, 56 m
depth, 1846-1926 EDT) andoff Charleston, South Carolina on 1 August 2002
(32.3°N, 79.0°W, 61 m depth, -1000 EDT). Behavior was as described by
Colin (1982), with the male displaying erect spines in the first dorsal fin, and
rapid pelvic-fin agitations. This display was directed at one or two nearby
females. Although Colin (1982) observed spawning from mid-afternoon to
sunset, we did not observe actual spawning in hogfish during dives in morning
and late afternoon. Bottom temperatures at the Florida site during the dive
Page 503
ranged from 20.90 - 20.94°C, considerably cooler than those reported by Colin
(1982) in December to March in Puerto Rico (24 - 26°C). Bottom tempera
tures at the South Carolina site ranged from 20.47 - 22.03°C.
77"W
Figure 21. Locations of capture of rock hind and yellowmouth grouper. See
Figure 2 for additional explanation.
Page 504
Figure 22. Locations of capture of speckled hind. See Figure 2 for additional
explanation.
Page 505
CONCLUSIONS AND MANAGEMENT ISSUES
Spawning condition was determined for 28 species of reef fish at several
phylogenetic levels, including Beryciformes (Berycidae), Scorpaeniformes
(Scorpaenidae), Perciformes (Carangidae, Centrolophidae, Haemulidae,
Lutjanidae, Malacanthidae, Polyprionidae, Serranidae, Sparidae) and
Tetraodontiformes, and over a considerable depth and latitudinal range. In
spiteof sometemporal and spatial sampling limitations, we determined thatthe
species examined fall into a few groups of life history and spawning strategies.
Several species, such as small serranids, haemulids, sparids and lutjanids,
spawned over protracted periods and throughout the region. Black sea bass,
sand perch, tomtate, red snapper, and vermilion snapper were broadly distrib
uted and spawned across the shelf, although vermilion snapper spawning
activity seemed to be more concentrated at shelf edge reefs than the other
species in this group.
Red porgy and bank sea bass also had broad distributions throughout the
region, but spawning appeared to be more narrowly focused on deeper sites in
the middle ofthe region. In the case of bankseabass, and to a lesser extentred
porgy, this may reflect sampling limitations as these both spawn in winter,
when sampling is more difficult and was subsequently more confined to the
waters near our laboratory.
Gag, scamp, red grouper, knobbed porgy and gray triggerfish spawned
mainly at shelf-edge reefs. Gag use shallow coastal or estuarine waters as
nursery areas, but make either an ontogenetic shift or spawning migration to
the outershelf. Tagging of gag has indicated a spawning migration (Van Sant
et al. 1994, McGovem et al. In press). Gray triggerfish juveniles are pelagic or
benthic in a variety of habitats (Martin and Drewry 1978), but apparently move
to deep reefs with age and maturity. Knobbed porgy, red grouper and scamp
appear to be more resident onouter-shelfreefs, where spawning occurs.
Tilefish, blackbelly rosefish, blueline tilefish, snowy grouper and yellow
edge grouper are resident, at least as adults, on the upper slope. Spawning is
restricted to reef(or mudinthecase of tilefish) habitats on theupper slope.
Barrelfish, wreckfish and red bream live on the Charleston Bump, mainly
in depths from 500 - 600 m (Sedberry et al. 2001, Popenoe and Manheim 2001,
Weaver and Sedberry 2001). Spawning also occurs there, under the main axis
of the Gulf Stream. Eggs, larvae and juveniles of wreckfish and barrelfish are
pelagic, perhaps living at the surface for several months (Sedberry et al. 1999,
Martin and Drewry 1978). It is uncertain how these fishes are recruited back
to the Charleston Bump. Juvenile wreckfish are very commonat the surface in
the eastern North Atlantic in the months following spawning on the Charleston
Bump, and wreckfish from the eastern North Atlantic are genetically identical
to those from the Charleston Bump (Sedberry et al. 1999, Ball et al. 2000),
indicating substantial gene flow between the regions, mediated by Gulf Stream
flow.
White grunt, and to a lesser extent red grouper, were collected in spawning
condition primarily in the northern part ofthe studyarea andapparently havea
disjunct distribution (Zatcoff et al. 2004, Chapman et al. In prep.). They are
abundant in the Caribbean and southern Florida, but are not common off
Page 506
northern Florida or Georgia. They appearto be more tropical species that are
found only in the waters of the northern SAB that are under the influence of
the Charleston Gyre. Because of the influence of Gulf Stream waters being
transported onto shelf waters off northern South Carolina and southern North
Carolina via the Charleston Gyre, many tropical species are recruited to this
area (Powell et al. 2000).
Gag and greater amberjack appear to undertake spawning migrations to
the south, with most spawning in greater amberjack apparently occurring off of
southern Florida. Tagging of these species off South Carolina has indicated
substantial movement to south Florida of large fish during the spawning season
(Van Sant et al. 1994, McGovem et al. In press, Meister et al. In prep.).
Several rare tropical groupers (yellowmouth grouper, rock hind, speckled
hind, graysby, coney, warsaw grouper) occur in the region, but it remains
uncertain if spawning in most of these is occurring here or if recruitment of
these fish comes from southern spawning locations. Groupers generally have
long-lived larvae [31 - 66 days (Lindeman et al. 2000)], and it is certainly
possible that periodic recruitment of these tropical species occurs. Some
females examined appeared to be in, or approaching, spawning condition;
however, it is unknown if population densities are high enough to induce
spawning behavior (aggregation, harem formation) that often accompanies
spawning in these tropical groupers (Jimenez and Fernandez 2001).
Although influenced by sampling limitations, there did appearto be areas
within the region that are spawning grounds for several species. Shelf-edge
reefs (40 - 60 m) in the middle of the SAB appeared to be particularly impor
tant. Some of these reefs coincide with areas proposed by the SAFMC as
MPAs that will prohibit bottom fishing (SAFMC 2004). Proposed MPAs that
encompass shelf-edge reefs off Charleston, South Carolina [SAFMC Proposed
South Carolina-B MPA, Option 1 at about 32.3°N (SAFMC 2004)] included
spawning grounds for bank seabass, red grouper, gag, scamp, knobbed porgy,
red porgy, vermilion snapper and gray triggerfish. Blueline tilefish were also
caught in spawning condition in this proposed MPA site,but most were caught
deeper, on upper slope reefs. Red snapper were also found spawning in this
proposed MPA, but extensive spawning was found scattered across the shelf.
Black sea bass and sand perch spawned near the South Carolina B sites, but
most spawning in those two species was at scattered middle-shelf reefs. Rock
hind spawned nearthis site andoccurred in the proposed SC-B Option 1 MPA.
Spawning in rock hind also occurred near Proposed South Carolina-A MPA,
Option 2 at about32.8°N,and rock hind werecollected at that proposed shelfedge MPA site. The two instances of courtship behavior observed in hogfish
also took place in proposed MPA sites, one of which was South Carolina B
(the other was Florida Option 1 off Jacksonville). The proposedMPA sites off
South Carolina appear to be particularly important as spawning grounds for
several species. Spawning occurred at one proposed South Carolina site
(South Carolina-B Option 1)during all months of the year.
Gag and scamp spawning occurred in more than one proposed MPA site
off South Carolina, and spawning scamp were caught in proposed MPA sites
off Florida too (SAFMC Proposed North Florida MPA Option 2 at 30°N).
Tomtate were found spawning at many mid- to outer-shelf sites, but only one
Sedberry, G.R. etal.GCFI:57 (2006)
Page 507
proposed MPA site (the North Florida Option 2 site) had spawning tomtate.
Vermilion snapperwere found spawning in almost all of the proposed sites, the
exceptionsbeing deep (> 200 m) sites off North Carolina and Georgia.
Several species spawned mainly on upper-slope habitats. Blackbelly
rosefish, snowy grouper, yellowedge grouper, and tilefish spawned on reef or
mud habitat centered around 200 m. Although tilefish spawned near one of the
proposed Georgia MPAs (SAFMC Proposed Georgia MPA Option 1), no
spawning in any of these deepwater species was detected within the proposed
MPA sites. Because protection and management of deepwater species is one
of the primary objectives of the proposed MPA sites (SAFMC 2004), consid
eration should be given to locating a deepwater site to coincide with known
spawning areas in deepwater species.
No spawning sites of greateramberjack coincided with proposed SAFMC
MPA sites. However, two spawning locations were within the Florida Keys
National Marine Sanctuary, but not within no-take zones in the Sanctuary.
Tagging data (Meister et al. in prep.) indicate substantial movement of greater
amberjack from the Carolinas to southern Florida during the spawning season.
The commercial fishery for greater amberjack is closed in April (see SAFMC
web site for regulations: www.safimc.net') and 56% of spawning fish were
collected in April (most ofthose from southernFlorida). This probably affords
considerable protection to spawninggreater amberjack.
Gag and red porgy are managed, in part, by a spawning season closure,
with commercial catches limited to the recreational bag limit for gag in March
and April (when 76% of spawning females were collected). Among several
other restrictions, sale of red porgy is prohibited from January through April,
when 88% of spawning females were collected. These closures during the
peak spawning season probably afford some protection to spawning gag and
red porgy.
Many species of reef fish spawn at shelf edge sites that are under the
influence of the Charleston Gyre. Eggs and larvae of these species are
probably entrained in this gyre. Gag larvae are most often collected in the
Charleston Gyre, often several tens of kilometers offshore and over much
deeper water (> 600 m) than their preferred (< 50 m) habitat (Sedberry et al.
2004). Spawning in the Charleston Gyre probably results in bettersurvival, as
early life history stages are carried off the shelf with its associated predators,
and are retained in a cyclonic circulation (with upwelling at its core) that
provides nutrients and eventual transported back ontothe shelftoward shallow
nursery areas. Such a strategy seems to be associated with the long larval
period found in groupers that spawn at shelf edge sites (Lindeman et al. 2000)
and that helps them utilize large gyres such as the Charleston Gyre.
Deep reef fishes of the Charleston Bump and Blake Plateau live and
spawn in areas beyond those currently proposed as MPAs where bottom
fishing would be prohibited. Wreckfish, however, are managed with gear
restrictions (no longlines), an individual transferable quota with total allowable
catch, and a spawning season closure (15 January through 15 April). Because
barrelfish spawn at about the same place, and their spawning season extends
into January (no data were available from February), it is likely that they are
afforded some protection during spawning by regulations imposed on the
Page 508
wreckfish fishery. Red bream, however, spawn in summer on the Charleston
Bump, when the wreckfish fishery is open and they are caught as bycatch.
There is no evidence that the apparently small (but undocumented) bycatch is
having a negative effect on spawning red bream, but this deserves further
investigation. In addition to spawnmg demersal fishes on the Charleston
Bump, there is some evidence that this is a spawning site for pelagic dolphin
(Coryphaena hippurus) and swordfish (Xiphias gladius) as well (Govoni and
Hare 2001, Sedberry et al. 2004).
Although many reef fishes important in commercial and recreational
fisheries off the southeastern U.S. spawn across broad shelf areas, it is evident
that some spawning is localized. Often, local spawning grounds are utilized by
several species. In deciding among options for final MPA sites, consideration
should be given to sitesthat are used as spawning grounds by several species.
It is obvious thatsome options among the MPA sites proposed by the SAFMC
contain more spawning sites for more species than do some of the other sites,
and that by minor shifts in location oreven orientation of the proposed closed
areas, more spawning fishes could be protected. Consideration of known
spawning areas and timesshould be an important criterion when planning time
or area closures to ensure sustained fisheries.
ACKNOWLEDGEMENTS
We thank scientists of the SCDNR-MARMAP program, past and
present (especially C. Barans, W. Bubley, J. Burgos, N. Cuellar, E. Daniel, K.
Filer, P. Harris, P. Keener-Chavis, D. Machowski, J. McGovem, S. Meister, J.
Moore, S. Palmer, P. Powers Mikell,W. Roumillat, C. Sharp, S. Van Sant,W.
Waltz, C.Wenner and B. White), for assistance in data collection and analysis.
Personnel of the NOAA Fisheries Beaufort Laboratory assisted with collection
of fishery-dependent samples. K. Grimball prepared most of the histological
sections and C. Schobemd provided observations of courtship behavior
observed during her analysis of submersible videotapes. M. Brouwer
(SAFMC) assisted with translations. Funding was provided by grants from
NOAA Fisheries, including MARFLN Grant NA17FF2874 (G. Sedberry,
Principal Investigator) and Unallied Science Program Grants NA97FL0376,
NA07FL0497 and NA03NMF4720321 (G. Sedberry, Principal Investigator).
Submersible observations were supported with grants from the NOAA Office
of Ocean Exploration (Grants NA16RP2697 and NA0ROAR4600055; G.
Sedberry, Principal Investigator). NOAA Fisheries has supported the SCDNR
since 1973 to collect the fishery-independent data used in this paper, underthe
SCDNR-MARMAP Program (current Grant 50WCNF106007-L0003; P.
Harris, Principal Investigator).
Page 509
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The Nassau Grouper Spawning Aggregation
Fishery of the Cayman Islands - An Historical and
Management Perspective
PHJLLIPPE G.BUSH1, E. DAVID LANE2, GINA C. EBANKS-PETRJE1,
KIRSTEN LUKE1, BRADLEY JOHNSON1, CROY MCCOY1,
JOHN BOTHWELL1, and EUGENE PARSONS1
' Cayman Islands Department ofEnvironment
P.O. Box 486 GT
Grand Cayman
2Fisheries andAquaculture, Malaspina University-College
Nanaimo, B.C. Canada
ABSTRACT
The reproductive characteristics of mass spawningat predictabletimes and
places have made the Nassau grouper, Epinephelus striates, vulnerable to over
fishing. Historically in the Cayman Islands, five Nassau grouper spawning
aggregations provided an important seasonal artisanal fishery for local fisher
men from which fish were harvested by the thousands. In 1986, fishermen
began complaining of reduced catch and size of fish taken from the fishery.
Since 1987, the fishery has been monitored. Data on age, size, catch, and
catch-per-unit-effort (CPUE) was collected. Fifty-two percent of fish aged
were seven and eight years old, indicating full recruitment to the fishery by this
age. Analyses ofdata show overall declines in catch, CPUE, and size. In 2001
a sixth aggregation was discovered and heavily fished. In 2002, an 'Alternate
Year Fishing' law was passed to reduce fishing mortality. In 2003, an 8-year
ban on fishing in all designated grouper spawning areas was implemented
when it became apparent tiiat further fishing could irreversibly compromise the
viability of the 'new' aggregation. Of the six known Nassau grouper spawning
aggregations sites in the Cayman Islands, three are fished out, two are in seri
ous decline, and one, though affected by fishing, is still comparatively healthy.
Additionally, two other areas were designated as potential spawning sites. The
Cayman Islands case is one typical of the depletion pattern of 'boom-and-bust'
Nassau-grouper aggregation fisheries seen throughout the region over the past
three decades. Despite the current ban on this activity locally, our goal is to
convince the local populace that this practice is unsustainable, and should per
manently cease.
KEY WORDS Nassau grouper, spawning aggregation, Cayman Islands, re
stricted marine areas
Page 516
EI Proceso de Apareamiento en las Islas Caimanes del Nassau
Grouper del Punto Perspectivo Historico y de Manejamiento
Las caracteristicas de reproduccion del Nassau Grouper (Epinephelus
striatus) en tiempos y lugares predictibles los ha hecho vulnerable a la sobre
pezca. En las Islas Caimanes historicamente 5 agregaciones de apareamiento
del Nassau Grouper proveian una importante pezca temporal. Sin embargo en
1986, los pezcadoreslocales comenzar6n a notar la reduccidn de la cantidad y
el tamano del pez obtenido.
La captura ha sido monitoriada por los ultimos 14 afios , durante este
tiempo los datos como la edad, tamano, cantidad y cantidad de unidad de
esfuerzo, fueron obtenidos y analizados. 52% de la edad de los peces fue 7
(26%) y 8 (25.9%) afios de edad, indicaron complete recruitamiento de este
grupo de edad en las pesca. Analisis de los datos senalaron todavia reduccion
en las pesca, CPUE, y tamano.
En el ano 2001 una Sexta agregacion fue descubierta y violentamente
pescada. En el 2002 una ley de altenar un ano de pezca fue obtenidad con la
idea de reducierla mortalidad. Pero cuando fue evidente que mas pescas hiban
a comprometer irreversiblemente la posibilidad de sobrevivencia de la nueva
argegaci6n se implanto una nueva ley de 8 afios de prohibicion de captura en
todas las areas designadas de apareamiente del Nassau Grouper.
De las seis conocidas agregaciones de apareamiento del Nassau Grouper
situados en las Islas Caimanes tres nan desaparecidos, dos nan declinado
seriamente y una a pesar del impacto sigue relativamente saludable.
Las Islas Caimanes es un caso tipico de las pollaciones de explotar sobre 3
decadas la abundancia de la pesca del NassauGrouper. A pesarde la prohibi
cion de la actividad pescadera local. Nuestra objective es de convencer y
educar la populacion local que esta practica es inconveniente y debe cesar
permanentemente.
PALABRAS CLAVES: Nassau Grouper, caracteristicas de reproduccion, las
Islas Caimanes
INTRODUCTION
The reproductive characteristic of aggregation spawning at predictable
sites and times have made the Nassau grouper, Epinephelus striatus (Bloch
1792), vulnerable to overfishing. As a result, many of the known spawning
aggregations of this species, areno longer viable (Sadovy and Eklund 1999).
The Cayman Islands (Grand Cayman, Little Cayman, and Cayman Brae)
lie between 19°15' and 19045'N latitude and between 79°44' and 81°27'W
longitude, and Nassau grouper are relatively abundant when compared to many
other locations (Patengill-Semmens and Semmens 2003). A traditional fishing
culture has evolved into one economically dependent on marine tourism and
finance over the past 30 years.
Historically, mere were five Nassau grouper spawning aggregation sites
(Tucker et al. 1993): one at the southeast comers of each of the three islands,
Page 517
Bush, P.G. et al. GCFI:57 (2006)
one at the southwestern comer of GrandCayman, and another at the southeast
comer of the Twelve Mile Banks west of Grand Cayman (Figure 1). Another
aggregation exists at Pickle Bank (44 nautical miles north of Little Cayman)
whose political jurisdiction is undetermined. The aggregations at the eastern
ends of the islands are the most well known, and have traditionally been
exploited sincethe early 1900s with the use ofsmallopen boatsand handlines.
In 1985, recognizing the importance of these three spawning areas, a general
license was issued under the Restricted Marine Areas (Designation) Regula
tions allowing access by residents, but restricting them to fishing by hook-andline only.
In 1986, increasing complaints from fishermen of a decline in both
numbers and size of fish taken from the fishery during the last several years
prompted the implementation of a monitoring program by the Department of
the Environment.
Atlantic ocmb
cult «(
riMlco
*^Cairaan
Inland*
«o
«
"P^\
Littla Cayman
A
Caynan
Brae
Brand Caysan
12 Mlla
Bank
A"
8
Spawning Sites
% Hiotorical
•
'Haw*
aV Potantial
«0 WWa
Figure 1. Map showing current Restricted Marine (Grouper Spawning) Areas,
(1) Grand Cayman - northeast point, (2) Little Cayman • northeast point, (3)
Cayman Brae - northeast point, (4) Grand Cayman -southwest point, (5) 12-Mile
Bank - northeast end, (6) Little Cayman - southwest point, (7) Cayman Brae -
southwest point, (8) 12-Mile Bank - southwest end.
Page 518
METHODS
From 1987 through 1992, data on catch, catch-per-unit-effort, and size,
were collected during spawning season from the three main spawning sites.
Catch data was recorded on a per boat basis. CPUE was determined by
dividing annual catch by the number of boat trips. Total length (TL) in
centimeters was measuredusing a graduated board.
Age data was obtained by analyzing sagittal otoliths taken from 479 fish,
and the agingtechnique was validated in 1992 by use of captive fish injected
with oxytetracycline (Bush et al 1996). Sampling of catch and size data from
the three mainaggregations continued through 2001. Sex andweightdata was
initially collected, but was discontinued due to manpowerand time restraints.
Data from the southwest point of Grand Cayman, Twelve-Mile Bank, and
Pickle Bank was sporadic and is not reported herein.
Fishery Data
Most grouper in the spawning aggregations (84%) are betweenthe agesof
six and 11 with 52%of the fish either ages seven (26.1%) or 8(25.9%). These
two dominant year classes (seven andeight) indicate the age at full recruitment
to the fishery (Figure 2). The oldest fish (29 years) exceeds the oldest age
reported for Nassau grouper (Olsen and LaPlace, 1978) by 13 years. A length
at age curve was generated (Figure 3) and fitted to the von Bertalanfry growth
equation in order to compare the equation parameters with those published for
E. striatus (Manooch 1987, Valle et al 1997). Loo, average asymptotic length,
= 765 + 30 mm with 95% confidence limits; K, growth coefficient, 0.282 (per
yr.); and to, theoretical age at 0 length, -0.638 yrs.; were calculated from a
regression of the Ford/Walford line (1 ,+[ = 140..04 + 0.821,, r2 = 0.96) to
where lt= lt+i; his the mean length at any given age. By restricting the ages
used to calculate the von Bertalanfry growth parameters to those with a
minimum of 10 fish in any age group (i.e., ages 5 -13) a close fit of calculated
and observed lengths was obtained between those ages (Table 1). Manooch
(1987), Pauly and Binohlan (1996), and Valle et al (1997) summarize parame
ters of Nassau grouper: L„ from 900TL -1130mmTL, with one exception (760
mm TL from NE Cuba, Claro et al 1991), K's from 0.060-0.224 (per year), and
to-3.27-0.488 (year). Our calculated growth parameters differ from those
published; Loo = 765 mm TL and to = -0.638, are lower than previously
published with the exception of one L«, estimate by Claro et al 1991. Our
growth coefficient K = 0.202 is slightly higher than those reported by
Manooch (1987), Pauly and Binohlan (1996), and Valle (1997), with one
exception, 0.224 reported by Randall (1962). The low L« and high K would
indicate that Nassau grouper around the Cayman Islands have a high early
growth rate to ages 10 or 11 but a lower terminal size than other stocks.
Page 519
130120
110
100
SO
& 80
g
70
| 60
u-
6040
3020-
10 |
o1-
—i——^—t—•—i—i—i—i
.
i
0 1 2 3 4 S 6 7 S 9 1011121314151617181920 2122 23 24 25 26 2728 29
Age (years)
Figure 2. Age frequency distribution of 479 E. striatus from 1987 -1992.
90-,
85
N
80
75
70
u
65
60
* T
e jw-I
S«>-
f)
?45o
'MeanTotal Length
-?40A
o 35
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30
25-
jn
20
15
10
5
0
1 2
3 4
5
6
7
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 24 26 27 28 29
Age (years)
Figure 3. Growth curve for E. striatus sampled from aggregations 1987 -1992.
Page 520
Table 1. Age vs. Length data of 479 Nassau grouper from the Cayman Islands.
Predicted mean lengths fitting the data between ages 5 and 13 to the von
Bertalanfry growth equation: It= 765[1-e-0.202(t+0.638)]
Age years
Total Lengths (mm)
No. Fish
Predicted
Length
Range
Mean
Standard
Deviation
0
150-180
1
230-290
268
4
340-445
408
42.3
6
398
5
365-585
478
72.7
14
465
520
-
-
-
2
93
4
216
6
360-630
541
61.1
52
7
345-710
570
48.2
125
565
8
490-695
599
45.4
124
601
9
530-750
638
54,1
45
631
10
555-720
646
42.8
25
655
11
540-750
663
57.2
31
675
12
620-710
704
47.9
15
692
13
660-760
713
34.1
10
705
14
600-735
716
50.9
9
716
15
565-820
722
87.2
6
725
16
660-760
714
-
4
733
17
810-840
827
-
3
738
18
801
743
21
782
28
850
29
810
-
-
1
-
-
1
753
-
-
1
762
-
-
1
763
Catch, CPUE, and Size from these three spawning aggregations have
declined over the 15 year period. Catch (Figure 4a) from Grand Cayman and
Little Cayman during the early years of the monitoring period was in the low
hundreds and has since dwindled. In Cayman Brae, while catch was in the low
thousands during the initial years following the re-discovery of the spawning
aggregation, it too has declined drastically in the lastsix years. Catch-per-uniteffort and size (Figure 4b,c) for all three islands show similar marked trends.
The LittleCayman site was abandoned in 1993 whenthe aggregation ceasedto
form.
—a— LftrJeCayman
" •" CaymanOne
Page 521
--*• -GrindCayman
^—Trand Lima Cayman - • - Trand Cayman Brae —• -Trend Grand Cayman!
B.
-Little Cayman
• «* CaymanBrae
-Trand time Cayman
Trend Cayman Buc
—*- -GrandCayman
Trand Grand Cayman
6500
~ . a*
.
6300
"^•-.
Si 00
a
oo
—•-Little Cayman
•«• Cayman Brae
—*• •Orand Cayman
Trand UM» Cayman •-• trand Cayman Brae —• -TrandGrand Cayman
Figure 4. 15-yeartrends in (A) Annual catch, (B) Annual catch-per-unit-effort
and (C) Annual size from the three northeastern grouper spawning aggrega
tions.
Page 522
Chronology of Fishing Activity
Between 1984 and 1990, the Cayman Brae site was dormant and the
fishing fleet of Cayman Brae targeted the northeast SPAG of Little Cayman
(the two islands are five nautical miles apart). In 1991, an aggregation was
found approximately 1.2 km north of the dormant Cayman Brae site, and has
been heavily fished.
By 1993, the Little Cayman site was inactive. Continued monitoring
through 2001 showed continuing declines in both catch and size of fish from
the aggregations of Grand Cayman and Cayman Brae. Of the two other
aggregations, located near Grand Cayman, one (Southwest site) was fished
until 1990, after which it no longer formed, and theother (Twelve-Mile Bank)
still yields a variable, albeit low, number offish.
In 2001, another aggregation which (according to anecdotal reports) had
not been fished since the late 1960s, was 're-discovered' at the western end of
Little Cayman, and heavily fished during the 2001 and 2002spawning season.
Approximately 4,000 fish were taken from thisaggregation during 20 days of
fishing (Whaylen et al 2004). Pre-fishing abundance for this aggregation is
estimated atover 7,000 fish. This aggregation isbelieved tobethe last healthy
spawning aggregation of Nassau groupers in the Cayman Islands.
Chronology of Management Measures
In 1995, after the first sixyears of data showed a decline in all parameters,
a recommendation was made to implement an 'Alternate Year Fishing'
strategy in order to reduce fishing mortality by half. However, due to lack of
politicalsupport,this was not implemented.
In 1998, the three main spawningareas at the eastern ends of the islands
were formally demarcated as 'Restricted Marine Areas' for which access
required licensing by the Marine Conservation Board (the statutory authority
responsible forthe administration ofthe Marine Conservation Law).
Following public controversy regarding the mass harvest of fish in 2001,
and again in 2002, the Marine Conservation Board and the Department of
Environment campaigned for support to protect the Nassau grouper spawning
aggregations byholding a series of meetings with government, the watersports,
and restaurant sectors of the Cayman Islands Tourism Association, as well as
fishermen. Protective legislation was passed inFebruary of 2002 (Whaylen et
al. 2004). This legislation defined a spawning season ofNovember 1 to March
31, and implemented the 'Alternate Year Fishing' law (first recommended in
1995) to reduce fishing mortality in the designated grouper spawning areas.
This law allowed fishing every other year with the first non-fishing year
starting with 2003, and also seta catch limit of 12 Nassau grouper perboat per
day during fishing years. The law also defined one nautical mile 'no trapping'
zones around each spawning site, and set a minimum size limit of 12 inches
for Nassau grouper. Finally, a significant aspect of the lawprovided power to
the Marine Conservation Board to change these restrictions to anyor all of the
designated spawning areas.
In mid-December of 2002, the other two of the five original spawning
areas, and the new one at the west end of Little Cayman, were designated as
restricted marine areas. In addition, two more areas were designated, due to
Bush, P.G. etal.GCFI:57 (2006)
Page 523
their potential to accommodate spawning aggregations, and the possibility of
spawning aggregations shifting. These were the southwest end of 12 Mile
Bank and the southwest end of Cayman Brae, both of which have the geo-
morphological and oceanographic characteristics common to such spawning
areas.
With the approaching spawning season of 2004, it was realized that the
new 'altemate-year-fishing' management strategy would not accomplish the
goal for which it was originally intended. Our calculations showed that,
despite the new catch limits, fishing during the 2004 season could compromise
the viability of this relatively healthy aggregation. Assuming that fishing
effort would be similar to that of 2001 and 2002, most of the estimated 3,000
surviving fish in the 'new' spawning aggregation at the west end of Little
Cayman, would be removed. As a result of this, on the 29lh December of
2003, the Marine Conservation Board exercised it powers to change the
'Alternate-Year-Fishing' portion of the law to an eight year ban on fishing
within all designated grouper spawning areas. It was thought that this time
period representing one reproductive cycle for the species, was the minimum
needed to realize any benefits to replenishment.
CONCLUSION
The Cayman Islands case is typical ofthe depletion pattern of 'boom-andbust' grouper aggregation fisheries seen through out the region over the past
three decades. Lack of effective management has resulted in the demise of
many spawning aggregations, including some local ones, and the species is
now absent in many locations.
It is important that fisheries management authorities be empowered to
respond quickly to problems as the timeliness ofthe response iscritical if it is
to succeed.
The seven year delay in implementation of the alternate year strategy,
combined with continued heavy fishing, almost certainly would have compro
mised the strategy's intended effect asreproductive stock became depleted.
The Cayman islands now have a total of eight designated grouper
spawning areas covering an area of17.56 square kilometers. Ofthe six known
Nassau grouper spawning aggregations sites in the Cayman Islands, three are
fished out, two are inserious decline, and one, though affected bytwo years of
heavy fishing, still relatively healthy. Despite the current ban on fishing local
aggregations, our goal is to convince residents that this practice is unsustain
able in any measure, and should permanently cease. Inthe interim, webelieve
that the management measures implemented, along with adequate enforcement,
will contribute effectively to the perpetuation of this species in the Cayman
Islands.
Immediate future plans for the Little Cayman aggregation include
continued in-situ monitoring, as well as a tagging and tracking project.
Eventually assessments will be carried out on all known spawning aggrega
tions sites, with a view to monitoring any replenishment or re-habilitation.
Other sites possessing other locations possessing similar geo-morphological
Page 524
and oceanographic conditions will also be investigated.
ACKNOWLEDGEMENTS
We would like to thank Brian Luckhurst, Will Heyman, and Yvonne
Sadovy for their expertise, advice, and dedicated support. In particular, we
appreciate their urgent letters of appeal to the Minister for Tourism, Environ
ment, and Developmentin support of protective legislation. Our gratitude also
goes to Leslie Whaylen and the REEF Team, whose assistance in monitoring
the 'new' spawning aggregation in Little Cayman was invaluable.
LITERATURE CITED
Bush, P.G., E.D. Lane, and G.C. Ebanks. 1996. Validation of Ageing Tech
nique for Nassau Grouper (Epinephelus striates) in the Cayman Islands.
Pages 150-157 in: F.A.Arrequin-Sanchez, J.L.Munro, M.C. Balgos andD.
Pauly (eds.). Biology, Fisheries and Culture of Tropical Snappers and
Groupers. Proceedings EPOMEX/ICLARM International Workshop on
Tropical Snappers and Groupers. October 1993.
Mannoch III, C.S. 1987. Age and growth of snappers and groupers. Pages 329373 in: J.J. Polovina and S. Ralston (eds.). Tropical Snappers and
Groupers, -Biology and Fisheries Management. Westview Press, Boulder,
Colorado USA.
Olsen, D.A. and J.A. LaPlace. 1978. A study of the Virgin Island grouper
fishery based on breeding aggregations. Proceedings of the Gulf and
Pattengill-Semmens, C.V. and BX Semmens. 2003. The status of reef fishes
in the Cayman Islands (BWI). Status of coral reefs in the Western
Atlantic: Results of initial Surveys, Atlantic Gulf Rapid Reef Assessment
(AGRRA) Program. Atoll ResearchBulletin496:226-247.
Sadovy, Y. and A.M. Eklund. 1999. Synopsis of biological information on
Epinephelus striatus (Bloch 1972), the Nassau grouper, and E. itajara
(Lichenstein 182) the jewfish. NOAA technical report NMFS 146, US
Department of Commerce. 65 pp.
Tucker, J.W., P.G. Bush, and S.T. Slaybaugh. 1993. Reproductive patterns of
cayman Islands Nassau grouper (Epinephelus striatus) populations.
Bulletin ofMarine Science 52:961-969.
Valle, S.V., Garcia-Arteaga, and R. Claro. 1997. Growth parameters of marine
fishes in Cuban waters. Naga, theICLARM Quarterly 20(l):34-37.
Whaylen, L., C.V. Pattengill-Semmens, B.X. Semmens, P.G. Bush, and M.R.
Boardman. 2004. Observations of a Nassau grouper, Epinephelus striatus,
spawning aggregation site in Little Cayman, Cayman islands, including
muti-species spawning information. Environmental Biology ofFishes 70:
305-313.
Primeras Descripciones de la Agregaci6n de Desove del
Mero Colorado, Epinephelus guttatus, en el Parque Marino
Nacional "Arrecife Alacranes" de la Plataforma Yucateca
ARMIN TUZ-SULUB1, KENNETH CERVERA-CERVERA2, JUAN C.
ESPINOSA MENDEZ2 y THIERRY BRULE1
1Laboratorio deIctiologia. CINVESTA V- IPN- Unidad Merida. Antigua
Carretera a Progreso Km 6. AP. 73 Cordemex
C.P. 97310. Merida, Yucatan, Mexico
2Centro Regional deInvestigacion Pesquera Yucalpeten. INP. SAGARPA.
Progreso, Yucatan, Mexico. C.P. 97320
RESUMEN
Desde el ano 2000 los primeros indicios de la ocurrencia de una agregaci6n de desove de mero Colorado E. guttatus en el Arrecife Alacranes fueron
puestos de manifiesto en trabajos realizados con Pescadores locales. A partir
del2002 y hasta el 2004, un area ubicada en el noreste del arrecife y conocido
como "el sandwich" fue monitoreado mensualmente en los dias previos y
posteriores a la fase lunar de luna llena. La determinacidn de la densidad de
organismos de E. guttatus enel sitio permitio definir que los meses deenero a
marzo son los meses pico de reproduccion de esta especie. La presencia de
ovocitos hialinos, observados macroscopicamente, en ejemplares hembras de
esta especie nos permitio confirmar laocurrencia deagregaciones dedesove en
esta area particular del Arrecife Alacranes. La talla de los organismos, que
fueron observados en la agregacion, correspondio a ejemplares adultos y
estuvieron entre los20 y 45 cm. de longitud total. La proportion de sexos fue
estimada en 1:1.3. La ocurrencia de este comportamiento reproductor fue
observada, en el mismo sitio y durante los mismos meses, durante el tiempo de
estudio. El area de agregacion esta ubicado a una profundidad de 85 pies y
presenta una cobertura dominante de corales suaves, principalmente gorgonias.
Datos de la explotacion pesquera deesta agregacion son incluidos y discutidos
en este trabajo.
PALABRAS CLAVES: Agregaci6n de desove, meroColorado, Yucatan
First Descriptions of a Spawning Aggregation of Red Hind,
Epinephelus guttatus, in the National Marine Park "Alacranes
Reef on the Yucatan Platform
Since 2000, first indications of the occurrence of a spawning aggregation
of red hind E. guttatus in the Alacranes Reef were identified through inter
views with local fishermen. From 2002 through 2004, an area located in the
northeast reef and known as the "sandwich" was monitored monthly during the
days prior to and after the Full Moon. The determination of density of E.
guttatus in the site allowed us to define that the months of January to March
Page 526
are the peak time of reproduction of this specie. The presence of hyalin
oocytes,observed macrocospically, in females examples allowed us to confirm
the occurrence of spawning aggregation in this particular area of the Alacranes
Reef. The size of the organisms observed in the aggregation corresponded to
adult organisms and were between the 20 and 45 cm. total length. The sex
ratio was estimated at 1:6 male:female. Reproductive behavior was observed,
in the same site and during such months, throughout the time of study. The
aggregation is located at a depth of 85 feet, andit displays a dominant coverof
smooth corals, mainly gorgonians. Fishing data are included and discussed in
this work.
KEY WORDS: Spawning aggregation, red hind, Yucatan
INTRODUCCION
Durante su epoca de reproduccion, los adultos de diversas especies de
peces tropicales de las familias Serranidae, Lutjanidae, Caesionidae, Mugilidae, Labridae, Scaridae, Acanthuridae y Siganidae forman agregaciones en
lugares especificos y periodos determinados, para liberar sus gametos. Estas
agregaciones constituyen unos de los ejemplos mas espectaculares de las
diversas estrategias de reproduccion que desarrollan los organismos presentes
en los ambientes de arrecifes coralinos. Una agregacion de reproduccion
puede ser definida como un amontonamiento de peces de una misma especie,
que se juntan para emitir sus gametos, y cuya densidad o cantidad de individuos es significativamente mas alta que la observada, en la misma zona de
agregaci6n, durante el periodo de inactividad sexual. Las investigaciones
sobre las agregaciones de reproduccidn de peces son escasas por el hecho de
que este tipo de estudio es generalmente dificil de realizar. A menudo son
eventos efimeros que ocurren en lugares muy remotos, muchas veces cuando
prevalecen condiciones climaticas desfavorables y, si suceden en zonasde facil
acceso, estas agregaciones ya desaparecieron o fueron reducidas en importanciaporla pesca (Domeier y Colin 1997).
Varias especies de meros(Epinephelinae, Epinephelini) realizan migraciones de reproduccion y forman agregaciones de centenares a miles de individuos durante varios dias, en sitios especificos de extension limitada, y a veces
en sincronia con las fases lunares (Domeier y Colin 1997). A la fecha se ha
podido comprobar la formaci6n de agregaciones de reproduccion tipicas para
E. adscensionis (Colin et al. 1987), E. guttatus (Colin et al. 1987; Shapiro et al.
1993a,b); Sadovy et al. 1994), E. itajara(Colin 1994), E. striates (Smith 1972,
Olsen y Laplace 1979, Colin et al. 1987, Colin 1992, Aguilar-Perera 1994,
Carter et al. 1994, Sadovy y Colin 1995, Aguilar-Perera y Aguilar-Davila
1996), M. bonaci (Carter 1989, Carter y Perrine 1994, Eklund et al. 2000), M.
tigris (Sadovy y Domeier 1994) y M. venenosa (Bannerot en Domeier y Colin
1997). Otras especies como M. microlepis y M. phenax forman agregaciones
mas modestas en cuanto al numero de individuos involucrados, y en areas mis
extensas (Gilmore y Jones 1992, Coleman et al. 1996, Koenig et al. 1996).
Algunas especies como Cephalopholis cruentata, Cfiilva y probablemente E.
morio no forman agregaciones para la reproduccion (Coleman et al. 1996).
Tuz-Sulub, A. et al. GCFI:57 (2006)
Page 527
Debido al hecho de que, ano teas ano, las agregaciones de reproduccion de
meros se forman muy a menudo en los mismos sitios geograficos y durante el
mismo periodo del ano, estas son particularmente vulnerables a la pesca
comercial. Las especies que presentan tal comportamiento de reproduccion
parecen muy propiciasa la sobreexplotaci6n pesquera(Sadovy 1997, Coleman
et al. 2000).
En el Banco de Campeche, se explotan comercialmente 17 especies de
meros de los generos Cephalopholis, Epinephelus y Mycteroperca (ColasMarrufo et al. 1998, Tuz-Sulub 1999). Ninguna agregacion de reproducci6n de
merosa sido reportada a la fecha parael Banco de Campeche, a pesar de que la
reproducci6n de varias especies ha sido observada en esta region (Brule et al.
1999, Renan 1999, Brule et al. 2000, Colas-Marrufoy Brule 2000, Renan et al.
2001). La formation de una agregacion de reproduccion de E. striatus en el
sur del Caribe mexicano, en Mahahual, Quintana Roo, constituye el unico
reporte actualmente disponible sobre este tema para las aguas mexicanas
(Aguilar-Perera 1994, Aguilar-Perera y Aguilar-Davila 1996). Estudios
previos en el parque Marino Nacional "Arrecife Alacranes", con barcos de la
flota pesquera yucateca, nos permitieron inferir que en esta zona arrecifal
podria estar ocurriendo agregaciones de desove de algunas especies de mero.
El propositi) del presente trabajo rue de determinar, a traves del analisis de
criterios directos como indirectos, si esta zona podria ser considerada como un
lugar potencial de agregaciones de reproduccion del mero Colorado Epinep
helus guttatus.
MATERIAL Y METODOS
Durante los afios del 2002 al 2004 se realizaron muestreos mensuales en
un area del Parque Marino Nacional Arrecife Alacranes. Estos incluyeron los
meses de reproduccion delmero Colorado, Epinephelus guttatus, reportadas en
la literature para la zona del Atlantico Oeste. En el area de muestreo el sitio
fue geoposicionado y descrito en funcidn desuscaracteres bioticos y abioticos.
Los muestreos se realizaron durante algunos dias posterioresa la fase lunar de
lima llena. Para Uevar a cabo la determination de la ocurrencia de agregacion
de desove del mero Colorado, se siguieron los metodos directos e indirectos
descritosen el manualdel SCRFA(2003). Para determinarla densidad de los
organismos se estimo el niimero de individuos de la especie distribuidos en un
transecto lineal de aproximadamente 100 mts de largo por un metro de ancho;
debido a las medidas de seguridad este area se reconocia en un tiempo no
mayor de 10 minutos de buceo con ayuda de equipo autonomo. Ademas en
cada inmersidn se observaron y describieron los patrones de coloracidn y
comportamiento de los organismos. Documentos de foto y video fueron
realizados con ayuda de camaras automaticas de 35 mm y 8 mm, respectivamente. Se caracterizo la cobertura de fondo del area estudiada y en cada
inmersidn se registraron los parametros de temperatura del agua y la profundi
dad promedio en la que se encontraban losorganismos.
Para confirmar la maduracion gonadal de los individuos observados se
colectaron algunos de ellos a travesdel arte de pesca de arpon hawaiano. Cada
ejemplar capturado fue sexado macroscopicamente y datos biometricos de
Page 528
Longitud Total, Peso Total y Peso de la Gonada fueron tornados en ellos. La
descripci6n macroscopica de las gonadas fue realizada con ayuda de los
criterios propuestos por Brule et al. (1999) para el E. morio, ademas se
realizaron analisis de tipo ponderal (indice gonadosomatico: IGS = 100*Pg/
Pe) para la comparacion con otros estudios de la misma especie.
RESULTADOS
Zona de la Agregaci6n
El lugar donde ocurre la agregacion se localiza en la zona de barlovento
del complejo arrecifal, a unos 200 metros de la barrera arrecifal, es conocida
localmente por los Pescadores como "Sandwich" debido a los restos de un
barco encallado cerca de esta zona. Geograficamente se localiza en los 29° 36'
LN y los 89° 43' LO cubriendo una extension de aproximadamente 1.5
kilometres cuadrados. El fondo marino, ubicado a una profundidad de entre 25
y 32 metros, presento un alto porcentaje de cobertura coralina viva, compuesta
principalmente por corales suaves (octocorales), hasta en un 60% de su
superficie; seguida por pequeiios parches de corales masivos de las especies
Montastraeaannularis y Diploria strigosa (30 %), la cobertura restante estuvo
compuesta principalmente por arena, roca y algas calcareas (10%). La
transparencia en el area fue siempre del 100 % con una visibilidad de hasta 30
metros. La temperatura del agua, a proximidad del fondo, fluctuo entre los
19.8CC (enero)y 25.8.°C (julio).
Caracteristicas de la Agregacion
Las observaciones submarinas directas permitieron determinar un gradual
aumento de la densidad de los organismos en el sitio de estudio. Los valores
mas altos fueron encontrados en el mes de febrero (133 individuos por
transecto en promedio) pero este aumento comienza desde el mes de diciembre
(1 individuo) y culmina en el mes de abril (6 individuos); los meses restantes,
de mayo a noviembre, se presento una densidad casi nula de E. guttatus en el
sitio de agregacion.
Los especimenes de E. guttatus presentaron un comportamiento gregario y
cambios en el patron de coloration. La agregacion de E. guttatus ocurrid en
pequeiios grupos de 6—8 individuos, a proximidad del fondo. En cada grupo,
uno de ellos, de tamano mas grande, siempre se ubico mis arriba de sus
companeros y del substrate con un comportamiento territorial. La mayoria de
los ejemplares con este comportamiento presentaron una coloration mas
palida, con ties barras oscuras ubicadas verticalmente a ambos lados del
cuerpo. Mientras los organismoscerca del fondo, en su mayoria eran hembras,
definidas claramente por el prominente abultamiento de sus vientres, presentaban un color uniforme palido, con puntos oscuros en todo el cuerpo, y un borde
oscuro en las aletas caudal, dorsal y pectorales.
Analisis Macroscdpico
Un total de 114 ejemplares fueron capturados, principalmente en los meses
de mayor densidad. Asi, macroscopicamente, se sexaron a 59 machos, los
Tuz-Sulub, A. etal. GCFL57 (2006)
Page 529
cuales estuvieroncaracterizados por la presenciade gonadas pilidas, las cuales
emitian esperma al someterlas a una presion leve. En 12 individuos no fue
posible llevara cabo un sexadomacroscopico debidoa que las gonadasestaban
en estado inmaduro y de muy pequeiio tamano, estos organismos fueron
catalogados como indeterminados. 43 hembras fueron identificadas debido a
una avanzada maduracion gonadal, caracterizada por la presencia de ovocitos
opacos y hialinos a simple vista. Lapresencia de ovocitos hidratados, macroscopicamente, nos permitio deducir que el desove en lashembras capturadas era
de manera inminente. Asi con los datos anteriores se obtuvo una proportion de
sexosde 1H:1.3M.
Las tallas de los organismos capturados fueron para los machos: Longitud
total minima y maxima de 34.8 y 48.5 cm., respectivamente. Las hembras
tuvieron un rango de talla entre los 26.5 y 35.3 cm. de longitud total minima y
maxima respectivamente. Los organismos categorizados como indeterminados
tuvieron una longitud total entre los 30.0 y 35.4 cm. minima y maxima
respectivamente. El analisis estadistico mostro diferencias entre la tallas,
siendo los macho mas grandes que las hembras y los indeterminados, y entre
estos dosultimos, el rango de tallas nopresento diferencias estadisticas.
El analisis ponderal del indice gonadosomatico revelo altos valores
individuates: las hembras tuvieron valores maximos y minimos de 38.2 y 2.8%
respectivos. Los valores para los machos fue de 2.76 y 0.35%, para los
organismos indeterminados estos fueron los mas bajos con valores de 1 y .19
% maximos y minimos respectivamente.
Por otio lado el analisis de la presencia de ovocitos hialinos en relation
con la fase lunar nos permitid observar que los mayores porcentajes relativos
del niimero de hembras con esta caracteristica se presentabanen dias posteriores a la fase de luna llena y mas cercanosa la fase de luna nueva.
DISCUSI6N
El reporte de la ocurrencia de agregaciones dedesove para una especie de
mero, Epinephelus guttatus, es el primero en su tipo de description que se
tiene para lazona delbanco deCampeche. Asi la determinaci6n deun periodo
de reproduccion de esta especie que ocurre entre los meses de enero a marzo
coincide con lo reportado para la misma especie en otra areas del Mar Caribe;
en particular, E. guttatus se reproduce entre enero y abril en Jamaica, Puerto
Rico y Venezuela (Colin et al. 1987, Shapiro et al. 1993a,b, Sadovy 1996). Las
variaciones mensuales observadas en el sitio, con un aumento bastante notorio
de la densidad en los meses antes mencionados es un detalle de caracter directo
que permite afirmar que efectivamente la ocurrencia de unaagregacion se esta
dando en el area (SCRFA 2003).
En los sitios donde ocurren estas agregaciones las caracteristicas de
coberturadel fondo con la dominancia de pequeiios parches de coral masivo y
corales suaves concuerda con lo que este estudio encontrd en la zona conocida
comoel "sandwich" (Colinet al. 1987, Shapiro et al. 1993a,b).
Se noto a traves de la realization de observaciones submarinas, la
formation de varios pequeiios grupos de individuos de E. guttatus dominadas
por un macho con su pequeno conjunto de hembras. Tambien se identificaron
Page 530
para los ejemplares de esta especie, patrones de coloration muy similares a los
descritos por Colin et al. (1987) y Shapiro et al. (1993a) para especimenes
machos y hembras de E. guttatusobservados en agregacion de reproduccion en
Puerto Rico. Sin embargo debido a la carencia de personal y las condiciones
meteorologicas de la zona de estudio no se pudo en algun momento observar
algun cortejo nuptial ni tampoco emision de gametos por parte de las organis
mos agregados.
A partir de del analisis macroscdpico de las gdnadas de los organismos
capturados nos confirmo que estaban sexualmenteactivos y se encontraban en
las etapas terminales de la vitelogenesis para las hembras o de la espermiogenesis para los machos. La presencia de un buen porcentaje de hembras con
ovocitos hialinos observados a simple vista durante el periodo de mayor
actividad reproductiva, nos permite determinar de manera concreta que los
organismos que ocurren en esta agregacion Uevaran a cabo un desove inminente (SCRFA 2003).
De manera general, se conoce poco sobre la ubicacidn geografica de los
sitios de reproduccion de los peces arrecifales de importancia comercial
(Sadovy, 1996). Sin embargo con todo lo anterior y considerando la clasificaci6n propuesta por Domeier y Colin (1997), podemos coincidir que para E.
guttatus realiza una agregacidn de desove de tipo Transitorias ocurren en
lugares ajenos al area de distribution habitual de los reproductores y implican,
por parte de ellos, la realization de migracionesde una duration de varios dias
o semanas. Estas agregaciones se forman durante varios dias o semanas
consecutivos, a lo largo de un periodo de tiempo limitado a uno o dos meses
del ano. Asi se reporta que E. guttatus forma agregaciones de reproduccion de
tipo Transitoria, que ocurren en sincronia con los periodos de luna llena, en
Bahamas, Belice y Honduras para la primera y en Bermudas, Belice, Puerto
Rico, Jamaica, y las Islas Virgenes para la segunda(Domeiery Colin 1994).
Se ha observado frecuentemente un uso compartido de los mismos sitios
de desove por parte de varias especies de meros y pargos pero en epocas del
ano diferentespara cada una de ellas. Tal es el caso de E. guttatus, E. striates,
M. venenosa y Lutjanus synagris en las bias Virgenes(Beets y Friedlanderen
Sadovy, 1996) o tambien E. striates, M. bonaci y L jocu en Belice (Carter,
1989). Al contrario, en otras regiones, como en las Bermudas, diferentes
especies desovan durante la misma epoca pero en sitios distintos: entre 33 y
37m de profundidad para E. striatus y entre 18 y 27 m para E. guttatus
(Bumett-Herkes en Thresher 1984).
Durante la formation de una agregacidn, la modalidad de apareamiento
(por pareja o en grupos) adoptado por los organismos de una especie determinada, puede ser deducida del valor de la proporcidn relativa que representa el
peso de los testiculos en relation con el peso de los machos (i.e. IGS). Los
machos de las especies que se reproducen a traves de la formation de parejas
presentan testiculos reducidos, de poco peso, y valores de IGS bajos; mientras
que los machos de las especies que desovan en grupos, presentan testiculos
muy desarrollados, de fuerte peso, y valores de IGS elevados. Los altos
valores maximos de IGS de machos de E. dejan suponer que estas especies
deben de desovar en grupos. Esta conclusidn confirma las observaciones
realizadas en otras regionessobre E. striatus pero contradice lo establecido
Tuz-Sulub, A. etal. GCFL57 (2006)
Page 531
para E. guttatus, lo cual es considerado como una especie cuyos individuos
forman parejas durante el desove (Domeier y Colin 1994). Con relation a M.
venenosa no se disponede reportesobre su modalidadde apareamiento.
Es necesario la realization de estudios mas detallados sobre la ocurrencia
de esta agregacion de desove en el Arrecife Alacranes, ademas estudios mas
avanzados en otras areas de la ecologia pueden poder articularse con la
ubicacion ahora concreta en tiempo y espacio de este fenomeno natural.
Actualmente la localization precisa de los habitats criticos donde se
forman las agregaciones de reproduccion asi como el periodo durante el cual
estas ocurren, son informaciones de suma importancia para pretender alcanzar
un manejo sustentable y la protection de especies de peces de alto valor
comercialy muy vulnerable a la explotacion pesquera, como son los meros.
AGRADECIMIENTOS
Al Consejo Nacional de Ciencia y Tecnologia (CONACYT) por el apoyo
financiero para la realization de este trabajo a traves del proyecto N° 37606-B
"Habitats criticos de algunos serranidos (Pisces: Perciformes) de importancia
Comercial de la plataforma continental de Yucatan". Al Lie. Rene H. Kantun
Palma, Director del Parque Marino Nacional Arrecife Alacranes, por todo el
apoyo logistico otorgado. Muy sinceramente a los senores Jose Luis Carrillo
Galaz, Felipe Alvarez Carrillo, Fernando Chan Teh, directivos de las coopera
tives "Fed. Reg. de Soc. Coops, de la Ind. Pesq. de la zona Centro y Poniente
del Edo. De Yucatin F.C.L.", "Pescadores de Sisal, S.C. de R.L." y
"Pescadores del Golfo de Mexico, S.C. de R.L." respectivamente, por todo el
apoyo brindado. A la IBA. Teresa Colas Marrufo y Biol. Esperanza Perez
Diaz, auxiliares de Laboratorio de Ictiologia, por todo el apoyo logistico
brindado en la realization de este trabajo.
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grouper, Mycteroperca tigris (Pisces: Serranidae). Copeia 1994:511-516.
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Neptune City, New Jersey USA. 399 pp.
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Cayman Islands Nassau grouper (Epinephelus striates) populations.
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los serranidos (subfamilia Epinephelinae) en el Banco de Campeche,
Yucatan, Mexico. Tesis de Licenciatura, Universidad Autonoma de
Yucatan, Merida, Mexico. 77 pp.
Estimation of the Size of Spawning Aggregations of Red Hind
(Epinephelus guttatus) Using a Tag-recapture
Methodology at Bermuda
BRIAN E. LUCKHURST\ JONATHAN HATELEY 2,
and TAMMY TROTT'
' Marine Resources Division
Department ofEnvironmental Protection,
P.O.BoxCR52,
Crawl CR BX, Bermuda
222 LongAcre, Delamere Park,
Cuddington, Norwich, UK
ABSTRACT
The estimation of the number of fish at a spawning aggregation site by
diver census can be logistically challenging.
The spatial extent of the
aggregation, underwater visibility, spawning time and other factors can
influence the accuracy ofthe estimate. We use the results of an extensive tagrecapture program for red hind (Epinephelus guttatus) at two spatiallyseparated spawning aggregation sites to estimate maximum aggregation sizes.
A total of three Peterson index values were derived from tag-recapture results
obtained at two seasonally-protected aggregation sites from 1993-2000. The
three maximum aggregation size estimates ranged from 926 to 1,153 fish.
These values are compared to estimates of red hind aggregation size from two
locations in the Caribbean.
KEY WORDS: Epinephelus guttatus, spawningaggregation size, Petersen
index, Bermuda
Valoraci6n del Tamano de Agregaciones de Freza de Mero
Colorado (Epinephelus guttatus) con una Metodologfa del
Etiqueta-recobrar en Bermudas
La estimation del niimero de individuos en bancos de desove usando
censos de buceo puede ser un desafio logistico. La extension especial del
banco de desove, la visibilidad subacuitica, el tiempo del desove y otros
factores pueden influenciar la exactitud de las estimaciones. Utilizamos los
resultados de un extenso programa de marcado y recaptura para mero cabrilla
(Epinephelus guttatus) en dos sitios de desove separados para estimar los
tamanos maximos de las agregaciones. Un total de ties valores del indice de
Peterson fueron derivados en los dos sitios protegidos durante la epoca de
desove durante el periodo 1993-2000. Las tres estimaciones del tamano
maximo de la agregacionvariation entre 926 a 1,153 individuos. Estos valores
se comparan con las estimaciones del tamano de las agregaciones de mero
cabrilla con otras dos localidades en el Caribe.
Page 536
PALABRAS CLAVES: Mero Colorado, Epinephelus guttatus,agregaciones
de freza, etiqueta-recobrar
INTRODUCTION
Reef fish spawning aggregations are documented throughout most of the
wider Caribbean region, and there appears to be a general declining trend in
landings from most known sites (Luckhurst 2004). The majority of the
landings from spawning aggregation sites are of the commercially important
groupers and snappers. Species from these two families comprise a significant
proportion of the landings from aggregations in most countries in the region.
Amongst the eight species of groupers known to form spawning aggregations
in the region (Luckhurst 2003), the red hind, a medium-sized grouper, is
known to form spawning aggregations in a number of countries including
Bermuda (Luckhurst 1998).
Domeier and Colin (1997) defined two different types of spawning
aggregations, "transient" and "resident". Groupers and snappers form
"transient" aggregations with the following characteristics:
i) Fish frequently migratelong distancesto the aggregation site,
ii) Aggregations typically form for only 1-3 months duringthe same time
periodeach year,
iii) The durationofthe aggregation ranges from only a few days to
several weeks,
iv) The formation ofaggregations is entrained to the lunarcycle with the
full moon periodappearing to be the most common aggregation time
for groupers and snappers in the wider Caribbean.
Due to the economic importance of groupers and snappers to most
fisheries, research to date has concentrated largely on the species in these two
families. However, relatively few spawning aggregations have been scientifi
cally evaluated. As a consequence of this paucity of quantitative information
from aggregation fisheries, it is difficult to evaluate aggregation status and
formulate appropriate management measures.
The estimation of fish abundance at spawning aggregation sites has been
conducted mainly by divers using various visual census techniques. Shapiro et
al. (1993) produced an estimate of the size of a red hind spawning aggregation
in Puerto Rico while Beets and Friedlander (1998) evaluated a red hind
aggregationin St. Thomas, U.S. Virgin Islands. More recently, Nemeth (2005)
has been documenting the recovery of this same red hind aggregation under
permanent closure.
In conducting visual counts, protocols are typically standardized to
minimize error and usually involve several divers and repeated counts.
However, there are still a number of problems associated with visual assess
ments:
i)
Underwater visibility - Poor visibility limits the field of vision for
diver counts.
ii) Spatial extent ofaggregation - Aggregations covering large areasmay
preclude the ability to survey the entire site during a given dive.
Luckhurst, B.E. et al. GCFI:57 (2006)
Page 537
iii) Depth limitations - Many aggregations occur in relatively deep water
(30+ m) limiting bottom time for divers.
iv) Temporal dynamics - Many aggregations are only fully formed just
before spawning occurs which is frequently approaching dusk, hence
low light conditions limit the ability of divers to make accurate
counts.
v) Sea conditions - It appears that spawning aggregation sites are
frequently in reef locations with strong currents and often rough sea
conditions, makingthe task ofworkingat these sites more difficult for
divers.
vi) Species behaviour - Some species swim in the water column making
them easier to count while others shelter in the reef infrastructure until
just prior to spawning and are notreadily observed by divers.
As a result of these problems, the use of underwater video cameras has
become a common means of providing a permanent record of the aggregation
and different videography techniques, e.g. freeze frame, can be used to
estimate the abundance of aggregating fish. This video record can then be
analyzed ata later date to examine detailed fish behaviour and other features of
the aggregation. Lastly, sonar scanning of aggregations has come into use in
recent years to estimate abundance. Thistechnique requires ground truth work
to interpret target size and strength in order to provide reasonable estimates of
aggregation abundance from sonar records.
The first research on spawning aggregations in Bermuda was conducted
on the red hind from 1973 - 1975 (Burnett-Herkes 1975). This research
program was initiated due to a request from commercial fishermen to take
management action in the face of the overfishing of aggregations. The
research involvedtagging andbasicbiologybut therewas very limited data on
spawning dynamics and no estimates of aggregation size were made. Sam
pling of the aggregations continued on anintermittent basis through the 1980s
but no tagging was conducted. Following the commencement of a long-term
tagging program in 1993, the initial results indicated a relatively high recapture
rate of tagged fish (15.2%) at the aggregation site and the recaptured fish
demonstrated site fidelity (Luckhurst 1998). This provided the opportunity to
use tag-recapture data to estimate aggregation abundance. Suitable data were
available for only three of the seven yearsofthe tagging program.
In this paper, we use a Petersen index to estimate abundance of redhinds
at two spawning aggregation sites at opposite ends of the Bermuda reef
platform.
MATERIALS AND METHODS
Sampling andtagging of red hinds from the northeastern (NE1) spawning
aggregation site (Figure 1) was conducted during the peak spawning aggrega
tion periods (full moon, May to July) in 1993 - 1995. At the southwestern
(SW1) site (Figure 1), sampling and tagging took place during the spawning
periods from 1997 - 2000.
Page 538
64 SOW
Figure 1.
Map of Bermuda reef platform indicating locations of the two
spawning aggregation sites (SW1, NE1) for red hind for which aggregation
abundancevalues wereestimated.
The details ofthe sampling and tagging protocolare outlined in Luckhurst
(1998). It should be noted that from 1994 onward, all specimens were doubletagged with Floy T-bar anchortags to minimize the effect of tag loss detected
after the first year of tagging. To evaluate the possible increased vulnerability
to predation of tagged fish upon release, the senior author observed (using
SCUBA) the release, on three separate occasions of tagged fish (total of >50
fish) while stationed on the reef substrate under the research vessel. Observa
tions were made of the behaviour upon release and tagged specimens were
tracked for the first 10-15 minutes post-release. The visibility of the tags while
fish were located within the reef infrastructure was also noted.
Following the theory outlined by Seber (1982), an estimate of maximum
aggregationsize is possible through the Petersonestimate, derived by;
N* = fa,+ l¥n,+ i.
(m2+l)
1
(1)
where N* = estimate ofthe number offish in a closed population
Page 539
n/ = number of fish tagged and released in the first sample,
n2 = number of fish obtained in the second sample
m2 = number oftagged fish in the second sample.
The variance (v*) ofN* is given by Seber (1982);
v* =
(nL+ !)(»>+ Hfai- y»2¥ii1- mj)
(2)
(m2+l)1(mI+2)
and an approximate95% confidence interval for N (the number of fish in a
closed population)canbe calculated by;
N* ± 1.96Vv*
(3)
Before substituting experimental values into equation (1), handling
mortality must be considered so that n,refers to the number returned alive to
the population (Seber 1982). An element of post-release mortality of tagged
fish probably occurred as a result of the invasive "winding" and tagging
procedures. Mortality due to capture and "winding" was estimated from the
proportion of red hinds that died while being retained in live-wells on board
the research vessel or in holding tanks ashore during a 24 hour minimum
observation period following capture. This time-period was selected as
experience indicated it to be the most vulnerable period of captivity. Data
from 1993 and 1994 indicated that the mortalityrate in captivity was approxi
mately 6%. Thus, the value substituted into equation (1) for survivorship of
tagged and released fish was reducedaccordingly.
RESULTS
Post-release Behaviour of Tagged Fish
Diving observations of tagged fish released overboard from the research
vessel indicated that all marked fish behaved in a similar manner.
Upon
entering the water, they oriented momentarily and then swam rapidly down
ward to the reef substrate where they sought cover under ledges or within
crevices in the reef infrastructure. Typically after 5-10 minutes, they left
shelter and moved slowly and cautiously away remaining close to the sub
strate. There were no observations of attempted predation on any tagged fish.
Aggregation Size Estimates
Suitable data from the tagging program to generate aggregation size
estimates was available for only one year at the northeastern aggregation site
(NE1) while two years data were available for the southwestern site (SW1)
(see Figure 1). Substituting values into equation (1) for the three data sets
providedestimatesof aggregation size (JV*)(Table 1). From equations (2) and
Page 540
(3), the 95% confidence limits for N, estimated from the variance (v*) of N*,
are given to provide estimates of maximum aggregation size (Table 1).
Given the similarity in these abundance estimates generated from the two
sites, it might be concluded mat they are similar in area. However, as diving
operationswere not made at the sites duringthe sampling and tagging periods
due to logistical constraints, there are no estimates of density of red hinds at
the two sites during the spawning periodswhich could be compared. It should
be recalled that both sites are seasonally closed to all fishing during the
spawning period (May - August) and thus receive the same protection.
Table 1. Petersen Index estimates of red hind aggregation size and maximum
aggregation size (using the 95% confidence interval) at two sites on the
Bermuda reef platform.
Aggregation
Year
Aggregation size (N*)
Maximum aggregation size
site
NE1
1993-94
639
926
SW1
1S97-98
712
1.153
SW1
1998-99
664
1.074
(95% CI)
DISCUSSION
Before comparing the aggregation size estimates obtained in this study
with the estimates for red hinds from locations in the Caribbean, it is useful to
evaluate the assumptions upon which the Peterson method is based in estimat
ing population size (N), ifN* is to be a suitable estimate ofN:
Thepopulation is closed (N is constant) — The spawningaggregations depart
from this assumption in severalways:
i) An estimate of mortality from the tagging process itself was not
obtained because fish were not retained for observation after tagging.
Thus, additional mortality may have occurred as a result of the
tagging process (e.g. infection of wounds around the tag site). There
may also have been increased vulnerability to predation as a result of
tagging although initial diving observations at the time of release did
not detect any. Thus, more tagged fish may have been removed
through incidental mortality than estimated (n/is too high), with the
net result ofoverestimating the aggregation size,
ii) Fishing mortality during the period between samples will remove fish
from the population.
In addition, recruitment probably occurred
between the two sampling periods as fish attainingmaturity joined the
aggregation. Seber (1982) states that when both recruitment and
mortality occur, N* will overestimate both the initial and final
population size.
Page 541
All fish have the same probability ofbeing caught in the first sample — Two
potential sources of bias could affect the composition of the first sample; the
area sampled and the catchability of the fish. Given that the spawning
aggregation sites were very limited in area (1-1.5 hectares) and the research
vessel was not static in relation to the anchor site, it is probable that all
portions of the aggregation site were fished. As catchability often varies with
the size of the fish, a variety of hook sizes and bait types were used to reduce
bias through gear selectivity. Studies on a red hind aggregation in southwest
Puerto Rico demonstrated that hook and line fishing provided an adequate
sampling technique both for sex ratio and size distribution within the aggrega
tion, as determinedby spearfisbing (Shapiro et al 1993).
The secondsample is a simple random sample — Two sources ofbias need to
be considered here; thorough mixing of the tagged andunmarked fish between
the sampling periods and the effect of tagging on catchability. Our data
strongly indicate that the aggregations dispersed and reformed between
sampling years thus resulting in thorough mixing of the tagged and untagged
fish. Multiple recaptures of red hinds were common at both sites providing
circumstantial evidence that catchability was not significantly affected by
tagging.
There is no tag loss between samples — During the early stages of the study,
tag obliteration was recorded and thus complete loss of the visible portion of
the tag probably also occurred. However, all specimens were double-tagged
from 1994 onward thus limiting the impact ofthis factor.
All tags are reported on recovery in the second sample — The only vessel
authorised to fish at the aggregation sites during the spawning season was our
research vessel. As the aggregation sites are both located in seasonally
protected areas, we believe that poaching by other vessels wasunlikelyand all
recaptures in the second sample wereprobably reported.
Given the above considerations, we believe that our estimates are reason
able first approximations ofred hind aggregation size in Bermuda.
There are three studies of red bind spawning aggregation size from the
Caribbean with which to compare our estimates. The first study was con
ducted in Puerto Rico by diver survey and the estimate of the size of the red
hind aggregation, based on a peak density of 7.6 fish/100 m1, was 745 fish
(Shapiro et al. 1993). This value is very similar to our values. The second
study, which was conducted in St. Thomas, U.S. Virgin Islands, yielded a
mean density estimate of 4.7 fish/100 m2 (Beets and Friedlander 1998) but did
not provide an estimate ofthe aggregation size. However, this density estimate
was obtainedtwo days after peak spawning and so is undoubtedly an underes
timate as red hinds appearto leave the aggregation site shortly after spawning
(Shapiro et al. 1993). As there is some uncertainty concerning the actual area
of the aggregation site in St. Thomas, we are unable to estimate aggregation
size. Given the area of the aggregation site and density values, a simple
extrapolation will produce an estimate of aggregation size. The population
Page 542
response of red hind to the permanent closure of this same aggregation site in
St. Thomas (Red Hind Marine Conservation District) was evaluated by
Nemeth (2005). He determined that the area of the red hind aggregation was
considerably larger than our Bermuda estimates (1-1.5 hectares) and that the
density of red hinds increased from 11.2 fish/100 m2 in January 2000 to 24.0
fish/100 m2 in 2003. As a consequence of these higher values, Nemeth (2005)
estimated that the spawning population size ranged from about 26,000 to
84,000 fish. These are extraordinarily high values when compared to the other
studies outlined here and may demonstrate the dramatic impact of a permanent
closure ofan aggregation site on the population.
The technique of mark / recapture has much potential for assessing
aggregation size, particularly if simple experiments to assess tagging mortality
and tag loss ratesare conducted to reducethe tendency for overestimationofJv*.
This technique can be a useful compliment to other methods of estimating
aggregation abundance particularly when on site abundance estimation is
challenging.
LITERATURE CITED
U.S. Virgin Islands. Environmental Biology ofFishes 55:91-98.
Burnett-Herkes, J. 1975. Contribution to the Biology of the Red Hind,
Epinephelus guttatus, a Commercially Exploited Serranid Fish from the
Tropical Western Atlantic. Ph.D. Dissertation, University of Miami,
Miami, FloridaUSA. 154 pp.
Domeier, M.L. and P.L. Colin. 1997. Tropical reef spawning aggregations:
defined and reviewed. Bulletin ofMarine Science 60:698-726.
Luckhurst, B.E. 1998. Site fidelity and return migration of tagged red hinds
(Epinephelus guttatus) to a spawning aggregation site in Bermuda.
Proceedings ofthe Gulfand CaribbeanFisheriesInstitute50:750-763.
Luckhurst, B.E. 2003. Development of a Caribbean regional conservation
strategy for reef fish spawning aggregations. Proceedings ofthe Gulf and
Luckhurst, B.E. 2004. Currentstatus of conservationand management ofreef
fish spawning aggregations in the Greater Caribbean. Proceedings of the
Gulfand Caribbean Fisheries Institute 55:530-542.
Nemeth, R.S. 2005. Population characteristics of a recovering U.S. Virgin
Islands red hind spawning aggregation following protection. Marine
Ecology Progress Series 286:81-97.
Seber, G.A.F. 1982. The Estimation of Animal Abundance and Related
Parameters. The Blackburn Press, 654 pp.
Shapiro, D.Y., Y. Sadovy, and M.A. McGehee. 1993. Size, composition, and
spatial structure of the annual spawning aggregation of the red hind,
Epinephelus guttatus (Pisces: Serranidae). Copeia 1993:399-406.
Status of a Yellowfin (Mycteroperca venenosa) Grouper
Spawning Aggregation in the US Virgin Islands
with Notes on Other Species
RICHARD S. NEMETH, ELIZABETH KADISON, STEVE HERZLIEB,
JEREMIAH BLONDEAU, and ELIZABETH A. WHITEMAN
Centerfor Marine andEnvironmental Studies
University ofthe Virgin Islands
2 John Brewer's Bay
St. Thomas, US Virgin Islands 00802-9990
ABSTRACT
Many commercially important groupers (Serranidae) and snappers
(Lutjanidae) form large spawning aggregations at specific sites where spawn
ing is concentrated within a few months each year. Although spawning
aggregation sites are often considered important aspects of marine protected
areas many spawning aggregations are still vulnerable to fishing. The
Grammanik Bank, a deep reef (30 - 40 m) located on the shelf edge south of St.
Thomas USVI, is a multi-species spawning aggregation site used by several
commercially important species of groupers and snappers: yellowfin
(Mycteroperca venenosa), tiger (M. tigris), yellowmouth (M. interstitialis) and
Nassau (Epinephelus striatus) groupers and cubera snapper (Lutjanus cyanopterus). This paper reports on the population characteristics of M. venenosa
with notes on E. striates and other commercial species. In 2004, the total
spawning population size of yellowfin and Nassau groupers were 900 and 100
fish, respectively. During recent years commercial and recreational fishing
have targeted the Grammanik Bank spawningaggregation. Between 2000 and
2004 an estimated 30% to 50% of the yellowfin and Nassau grouper spawning
populations were removed by commercial and recreational fishers. These
findings support the seasonal closure of the Grammanik Bank to protect a
regionally important, multi-species spawning aggregation site.
KEY WORDS: Marine protected areas, reef fish spawning aggregations,
fisheries management
La Condicidn de Agregaciones Reproductivas de Cuna
Cucaracha y Mero Gallina: Din&mica de una Multi-especie
Agregacion Reproductiva en el USVI
Muchos meros (Serranidae) y pargos (Lutjanidae) forman agregaciones
reproductivas en sitios especificos por un par de meses cada ano. Aunque sitios
de desove se consideran un aspecto importante de areas marinas protegidas,
muchos agregaciones reproductivas son vulnerable a la pesca. El Banco de
Grammanik se usa por varias especie comercialmente importante de meros y
pargos. Es un arrecife profundo (30 - 40m) localizado en el sur de los USVI y
Page 544
es un sitio que tiene una multi-especie agregacion reproductiva. Buzos han
documentado el desove de cuna cucaracha (Mycteroperca venenosa), cunas
(M. tigris y M. interstitialis), mero gallina (Epinephelus striates) y el pargo
guasinuco (Lutjanus cyanopterus). Durante aiios recientes, Pescadores
commerciales y recreativas han concentrado en la agregacion reproductiva de
cuna cucaracha. La pesca amenaza no s61o esta especie pero tambien el mero
gallina, que se extirpo localmente en el los 1980s, pero puede ser que se
recupera en este sitio. Este manuscrito describe los cambios anuales y
estacionales en abundancia, la utilization del habitat, y describe las caracteris
ticas de la poblacidn reproductiva del cuna cucaracha y mero gallina.
PALABRAS CLAVES: Areas marinas protegidas, agregaciones de desove,
las Islas Virgenes de los EEUU
INTRODUCTION
Many commercially important groupers (Serranidae) form large spawning
aggregations at specific sites and at which spawning is concentrated within a
couple of months each year (e.g. red hind Epinephelus guttatus and Nassau
grouper E. striatus (Colin et al. 1987), tiger grouper Mycteroperca tigris
Valenciennes (Sadovy et al. 1994). These spawning aggregations may be the
primary source of larvae that replenish the local fishery through larval
retention and recruitment (Sadovy 1996).
In the late 1970s and early 1980s, unregulated fishing on grouper spawn
ing aggregations sites throughout the U.S. Virgin Islands led to the extirpation
of Nassau grouper and brought the red hind grouper population to the verge of
collapse (Olsen and LaPlace 1978, Beets and Friedlander 1992). In 1990,
through the recommendations of the Caribbean Fisheries Management Council
and support of local fishers, two important red hind spawning aggregation sites
(Red Hind Bank, St. Thomas and Lang Bank, St. Croix) were closed season
ally during spawning to protect the breeding populations of red bind. In 1999,
the Red Hind Bank Marine Conservation District (MCD) was established as
the first no-take fishery reserve in the USVI. Recent evidence suggests that the
closure of the Red Hind Bank has been successful in protectingthis spawning
subsection of the population. By 1997 the average size of spawning hind had
increased by over 6 cm (Beets & Friedlander, 1998). Even more impressively,
the number of spawning individuals increased dramatically from 4.5 fish /100
m2 in January 1997 to 23 fish /100 m2 in January 2001 (Beets and Friedlander,
1998, Nemeth 2005). Similar responses to protective management measures
have been shown for other species throughout the Caribbean (Bohnsack 1990).
Unfortunately not all grouper spawning aggregations are afforded the neces
sary protection to sustain their populations.
Prior to the year 2000, the Grammanik Bank was known as a deep coral
reef bank utilized by local commercial fishermen. Commercial fishermen
knew of the existence of a yellowfin grouper spawning aggregation but did not
harvest these fish since they were known to contain ciguatera poisoning. In
February 2000, scientists at the University of the Virgin Islands first surveyed
the Grammanik Bank as partof a study to compare fish populations inside and
Nemeth, R.S. et al. GCFL57 (2006)
Page 545
outside of the Red Hind Bank Marine Conservation District (Nemeth and
Quandt 2004). Considerable attention was focused on this deep coral bank
when commercial and recreational fishermen landed an estimated 10,000
pounds of yellowfin grouper within a week following the full moon in both
March 2000 and 2001 (K. Turbe Personal communication). These unusually
large catches of grouper were verified in monthly commercial catch reports
(USVI Division of Fish and Wildlife, unpublished data). It was also reported
that manyof these yellowfin grouper weregravid with well developed ovaries
(H. Clinton, Personal communication) andthatmany Nassau grouper were also
caught asbycatch and sold. It wasestimated that over500 M. venenosa and50
E. striatus were removed from the spawning aggregation each year. Following
collapse of the Nassau grouper fishery in the late 1970s there has been no
known spawning aggregation for this species on the shelf south of St. Thomas
or St. John. Currently, a lack of enforcement at this site could mean the
collapse of the yellowfin grouper and/or the delayed recovery of the Nassau
grouper population which may be re-forming a potentially spawning aggrega
tion at this site. Although the Grammanik Bank was recommended for closure
as early as November2000,the Caribbean Fisheries Management Council has
only recently approved an interim seasonal closure of the Grammanik Bank
from February through April 2005. The data presented in this paper provides
baseline spawning population information on these vulnerable grouper species
and will allow an assessment of the response of these grouper populations to
the recent protective measures.
METHODS
Locate Primary Spawning Aggregation Site
To locate the primary spawning aggregation sites of M. venenosa and E.
striatus within the Grammanik Bank, the entire bank was surveyed using scuba
and underwater scooters several days before and after the full moon in March
2003 and March and April 2004. GPS coordinates were recorded by a boat
following a diver-towed surface buoy to determine the area ofthe bank.
Grouper Spawning Density, Fish Size, and Behavior
Diver surveys were conducted between February 2001 and August 2004.
Since several species of groupers and snappers are particularly wary and tend
to swim away from divers prior to being counted along a transect line (RSN,
personal observations), a combination of belt transects, stationary point counts,
and roving diver searches were used to accurately estimate fish densities as
well as total spawning populationsize of all commercially important Serranids
and Lutjanids. Point counts were conducted by recording all fish within a 10
m radius of a stationary diver for a period of four minutes. Belt transects were
30 m x 2 m and conducted by swimming along the linearaxis of the reef while
a transect tape unreeled behind the diver. The size of all fish observed along
transects or point counts were estimated in 10 cm size classes. Roving diver
searches were typically constrained by scuba limits at deep depths, and
therefore, were conducted for periods of 15 minutes. Roving divers would
Page 546
swim at a constant speedand survey a 10 m widearea while towinga surface
buoy. These roving dives allowed reasonably accurate estimates of total
population size since diverssurveyed non-overlapping areas ofthe narrowreef
(<100m wide)and several sequential dives couldcoverthe entire length of the
Grammanik Bank (1.69 km).
Tagging and Population Sex Ratios
BaitedAntillianfish traps and hook and line wereused to collect groupers.
Due to the depth from which the fish were collected, expansion of air within
their gas bladders resulted in buoyancy problems and occasional embolisms.
A sterilized large-bore hypodermic needle was used to extract gas from the
over-inflated air bladder. Once buoyancy was restored, each fish was meas
ured for total length (to the nearest mm) and tagged through the dorsal fin
pterygiophores with a numerically-coded Floy dart tag (FT-2). Dart tags
contained the following information: identification number, reward $20,
University of the Virgin Islands, and a contact telephone number. The
recapture location of returned tags provided information on distance travelled
by fish departing the aggregation site and a detailed picture of the source of
spawning groupers. Prior to release,the gender of each fish was determined by
using ultrasound and by gently squeezing the body wall above the vent to
extract milt and possibly eggs. Fish were released using a release cage which
could be remotelyopened once the cage reached the sea floor, thus minimizing
mortality due to predation and ensuring re-pressurization ofgroupers.
RESULTS
Location of Primary Spawning Aggregation Sites
The Grammanik Bank lies on an East-West axis at the edge of the insular
shelf south of St. Thomas, USVI (Figure 1). The bank extends 1.69 km at its
longest point (between 18°11.30N, 064°57.50W and 18°11.60N, 064°56.60W).
During visual surveys the northern and southern margins were clearly visible,
and the bank was estimated to be less than 100 m wide for virtually its whole
length. Depths on the coral reef varied between 35 and 40 m and the coral bank
is bordered to the east and west by shallower (25 to 30 m) hard-bottom ridges
along the shelf edge, sparsely colonized by corals, gorgonians and sponges.
The bank is bordered to the north by another coral bank and to the south by the
steep drop off. The primary spawning aggregation site for M. venenosa was
discovered on April 9, 2004. It was located over colonized hard bottom
approximately 300 m west of the dominant coral reef. During this same time
period, we observed Nassau groupers, some with the bicolor spawning
coloration and others with visibly extended abdomens. This presumed
spawning aggregation site for E. striatus encompassed the west end of the
coral reef bank to the M. venenosa site. A spawning site for M. tigris was also
located at the western tip of the coral reef bank. A spawning site for M.
interstitialis was located along the southwestern margin of the coral reef bank.
Finally, the spawning site for Lutjanus cyanopterus, the cubera snapper,
Nemeth, R.S.etal. GCFI:57 (2006)
Page 547
««?•
/
^
^^:^.
\
'/
i
aS*^
"J/
Figure 1. Map of the Northern Virgin Islands showing location of the Gram
manik Bank(*) and the Marine Conservation District (MCD) along the southern
edge of the insular platform. Dashed line shows 100 fathom depth contour.
Grouper Spawning Density, Fish Size, and Behavior
Visual surveys (belt transects andpoint counts) were conducted on various
dates from February 2000 to August 2004but mostwere done around the full
moon from February through April in each year (Table 1). Densities of
commercially important groupers varied considerably between months and
years (Figure 2). M. venenosa densities were highest in March 2003 and April
2004, E. striatus and M. interstitialis densities peaked on March 2002 and
March 2003, respectively, and M. tigris showed high densities in April 2001
and 2004 and February 2002 (Figure 2, Table 1). From December 2002
through February 2003 the densities of M. venenosa and E. striatus were very
low, and there was no evidence that these species were aggregating. While
densities of most groupers remained the same throughout March 2003, the
average density of M. venenosa increased almost fourfold (Table 1) by 19
March, one day after the full moon (Table 1). Whether this represents an
overall population increase or clustering of individuals towards a single
location was unknown. With the exception of M. tigris, all other serramds
departed the Grammanik Bank aggregation site by early April 2003 (Table 1).
Throughout March 2004 point counts provided fairly consistent estimates of
grouper densities (Table 1). However, observations offish behavior indicated
that as evening approached groupers began to depart their daytime positions,
suggesting that fish were possibly moving toward the actual spawning
aggregation site. Since point counts were not effective at locating the spawn
ing aggregation site, scooter surveys were primarily utilized throughout April
2004.
Tablel. Grouper density (#/100m2 ±SD) from belttransects and point counts on the Grammanik Bank, St. Thomas USVI, between
February 2000 and August 2004. Dashed lines indicate that no data was collected using that method. N = number of transects or
point counts.
Date
|
M. vene
E. striatus
Point counts
I
Belt transects
N
M. tigris
nosa
M. interstitialis
N
M. vene
£ striatus
M. tigris
M. interstitialis
nosa
^Mtsm^^^^^^^^m^^^^^^^^^^^k^^^^^^m^^^^^^^m^^
17 Feb
6
0
0
0.28 ±0.68
0
-
-
-
Kt^lillJliiisiSs! SKiiliftllllmimmiimsmmm
mmmmmmmmm WSMwMMSMm!
11 Apr
3
0
0
2.54 ±2.54
0
19 Jul
6
0
0
0.28 ±0.68
0
6 Sep
6
0.28 ±0.68
0
0
0.28 ±0.68
1Mar
4
0
2.78 ±2.54
2.22 ±1.92
0
27 Mar
15
0.83 ±2.41
0.68 ±2.50
0.28 ±0.65
0
18 Dec
-
-
6
0.21 ±0.26
0.05 ±0.13
Tablel (conL). Grouper density (#/100m ± SD) from belt transects and point counts on the Grammanik Bank, St. Thomas
USVI, between February 2000 and August 2004. Dashed lines indicate that no data was collected using that method, n = number of transects or point counts.
M. vene
E. striatus
M. tigris
nosa
M. interstitialis
12 Feb
0.21 ±0.60
0.42 ±0.77
0.42 ± 0.77
0.21 ±0.59
4 Mar
0.67 ±0.91
0.33 ± 0.75
0
0.83 ±1.39
18 Mar
19 Mar
3 Apr
11 Dec
m
7 Jan
0
0.83 ±1.18
0.21 ± 0.59
N
M. vene
E. striatus
M. tigris
M. interstitialis
0
0.42 ±0.74
nosa
o
3
2.23 ± 0.32
0.32 ±0.32
7
2.64 ± 0.57
0.41 ±0.70
0.50 ±0.55
0.27 ±0.22
2
0
0
0.16 ±0.22
0
70
0
©
•
SL
0.21 ±0.59
27 Feb
0.47 ±0.68
0.16 ±0.22
2 Mar
0.32 ±0.36
0.06 ±0.13
0.13 ±0.23
3 Mar
0.38 ±0.35
0.13 ±0.28
0
4 Mar
0.21 ±0.18
0.21 ±0.37
0
5 Mar
0.32 ±0.32
0.20 ±0.26
0
7 Mar
0.64 ±0.64
0.17 ±0.22
8 Mar
0.32 ±0.45
O
0.08 ±0.14
o
Tl
IB
e
o
0.26 ±0.24
0
0
0
12 Mar
0
0
1.75 ±0.68
0
13 Mar
0.25 ±0.14
0.13 ±0.17
2.80 ±1.68
0
12 Apr
2.02 ±0.80
0
0
0
D)
Page 550
Nassau
E
o
n
o
n 0
JO
ia_L
o
e
10
c
Q
31
Yellowmouth
2
1
n n 0
OOn
B|o
• _o
2001
2002
2003
2004
0
Year
Figure 2. Density of four spawning grouper species: yellowfin (Mycteroperca
venenosa), Nassau (Epinephelus striatus), tiger (M. tigris) and yellowmouth (M.
interstitialis) for February, March and April 2001 to 2004. n = no data, 0 = no
fish seen. Calculated from pointcounts and transects.
During roving diver surveys of the whole bank on 11 and 12 March 2003
(sbc days prior to the full moon), the highest density of M. venenosa was seen
in a small (approximately 50 m2) section of the bank. Other individuals were
observed scattered across the reef and the total population estimate for M. ve
nenosa grouper at this time, across the entire bank, was about 50 individuals.
Population estimates for E. striatus, M. tigris and M. interstitialis for March
2003 were 5,7 and 13 groupers, respectively.
Nemeth, R.S. et al. GCFC57 (2006)
Page 551
More frequent roving diver surveys in April 2004 (full moon on April 5)
improved our population estimates for M. venenosa and M. tigris (Figure 3).
Total population estimates for E. striatus declined dramatically from March to
April 2004 and may have been a result of fishing mortality from the three to
five fishing boatsseenon the bank eachday over the courseof severalweeks.
1000
800
600
400
Yellowfin
••I •! I
200
100
c
o
•mm
13
80i
40
20
3
a
o
a.
Nassau
60
I
-••
-I
w.f mil,
. I.
100
80
Tiger
60
c
40
c
20
mmm
li *
a
co
Date
Figure 3. Total population size for four spawning grouper species: yellowfin (M.
venenosa), Nassau (£. striatus), tiger (M. tigris) and yellowmouth (M. intersti
tialis) for March 11 (grey bar) and April 2-13, 2004 (black bars). The spawning
aggregation sites were discovered on April 8 for E. striatus, M. tigris and M.
interstitialis groupers and on April 9 for M. venenosa grouper. Full moon was on
April 5,2004.
Page 552
The presumed spawning aggregations of M. venenosa, M. tigris, M.
interstitialis and E. striates were observed on April 8 to 13, 2004. During
2004, M. venenosa occurred in a large aggregationwhere about 50% to 75% of
the fish were swimming two to five meters above the bottom, and the remain
der swam near the bottom. Several color phases of M. venenosa were ob
served. The most commonincluded the typicalcolor pattern of irregularblack
spots on a white background. On other individuals, the dark spots were
obscured on the dorsal half of the body by a deep red color. A final color
partem included fish with light colored head, white caudal fin with wide black
margin and bright yellow on the margins of the pectoral fins and on the lips.
Otherindividuals were observed with intermediate forms ofthese colorphases.
No spawning or courtship was observed for M. venenosa. E. striatus were
noted in loose groupings and as pairs with one individual, presumably a male,
in the bicolor phase and the other individual, presumably a female with visibly
extended abdomen, displaying normal barred color pattern and resting on the
bottom. At the Grammanik Bank only four of 60 E. striatus were seen
displaying bicolor phase, but no courtship or spawning was observed. The bi
color phase male was observed either displaying laterally to the female,
hovering one to two meters above the female, resting near the female on the
bottom or swimming alone one to two meters above the bottom. M. tigris and
M. interstitialis spawning aggregations had similar behavioral traits where
about half of the individuals were hovering two or three meters above the
bottom while the remainder where near the bottom among coral colonies. M.
tigris was observedwith three distinctcolor phases. Dominantmales had pale
yellow head, dark speckled body, and white patch with black spots on the
ventral posterior portion of the body and base of anal fin. These fish were
often observed cruising or hovering two to four meters above the bottom or
displaying courtship behaviors to females which had distended abdomens.
These resumed females displayed the barred color pattern typical of M. tigris
and were typically seen swimmingslowly or resting near the reef. A third color
phase included smaller individuals with the typical body stripes obscured by a
darkened body. These individuals were typically seen hovering two to three
meters above the reef. M. interstitialis were observed with a bicolor phase
similar to that of£ striatus and a lighter color phase typical ofM. interstitialis.
Both color phases were seen either resting near the bottom or hovering two to
three meters above the reef. Courtship was not observed for M. interstitialis.
Spawning was not observed for any ofthese grouper species.
The Grammanik Bank was surveyed for several months following the
grouper spawning season in 2003 and 2004. In April 2003, one day after the
full moon, more than 50 cubera snapper (Lutjanus cyanopterus) were observed
during a roving survey. On the full moon in May 2003, divers estimated more
than 300 L. cyanopterus on the bank. Three days following the full moon in
June the population of L. cyanopterus on the Grammanik bank had declined to
approximately 150 fish. The spawning season shifted from April to June in
2003 to June through August in 2004 (Figure 4). During the daytime several
large (20 to 100 fish) roving schools of I. cyanopterus were observed through
out the bank with snappers most often concentrated on the northern margin of
the bank. Toward evening roving schools of L. cyanopterus joined into one
Nemeth, R.S. et al. GCFI:57 (2006)
Page 553
large school and fish displayed intensifying courtship interactions and
spawning. Schoolmaster snapper (L. apodus) were also observed in large
numbers in April (n = 180) and July (n = 120) 2004 but no signs of courtship
or spawning was observed.
MAR
APR
MAY
JUN
JUL
AUG
Month
Figure 4. Total population size of cubera snapper (L cyanopterus) spawning
aggregation on the Grammanik Bank from March to August 2003 and 2004.
Size estimates of groupers from fish transects and point counts
(categorized into 10 cm increments) ranged from 30 to 80 cm total length
while mean lengths for M. venenosa, E. striatus, M. tigris andM. interstitialis
were 53.2 cm, 45.6 cm, 47.0 cm and 43.7 cm, respectively. More detailed size
frequency distributions and sex ratios were obtained from 28 M. venenosa and
62 E. striatus during trap and hook and line fishing. Male M. venenosa were
significantly larger than females (ANOVA: F = 16.4, p < 0.001, Figure 5).
Female to male sex ratio was nearly 1:1 for M. venenosa. The length of both
sexes of E. striatus were nearly identical (ANOVA: F = 0.48, p > 0.50, Figure
5) but the female: male sex ratio was 2.4:1. Ultrasound analysis of M.
venenosa and E. striates showed that females and males of both species had
well developed gonads with males of both species running ripe and females
with hydrated eggs. During sampling in March 2004, two Nassau (male and
female) and two male yellowfin groupers died due to air embolism. In April
2004, two additional Nassau groupers died. These last two fish were brought
back to the lab and examined.
The female was 55.9 cm total length and
weighed 3,442 g. Its ovary weight and volume were 426 g and 410 ml,
respectively. The male Nassua grouper was 64.8 cm total length and weighed
4,996 g. The weight of its testes was 322 g. A total of 23 yellowfin and 60
Nassau groupers were tagged and released on the Grammanik Bank between 8
March and 9 April, 2004. To date, no tagged groupers have been recaptured
and returned to UVI for reward.
Page 554
Mycteroperca venenosa
10
GsEEJ Female (mean = 64.5 cm, n = 13)
•••
Male (mean = 75.4 cm. n = 15)
8
<D
6
E
3
4
w
2
0
Epinephelus striatus
20
es23 Female (mean = 59.1 em, n = 44)
•••
Mate (mean = 60.3 cm, n = 18)
////////
Size class (TL mm)
Figure 5. Size frequency distributions and gender for yellowfin (M. venenosa)
and Nassau (E. striatus) groupers from the Grammanik Bank spawning
aggregationsite in April 2004.
DISCUSSION
In March 2000 and 2001, the yellowfin grouper spawning aggregation on
the Grammanik Bank was heavily targeted by local commercial and recrea
tional fishermen. At this same time many Nassau grouper were also being
caught as bycatch (K. Turbe Personal communication). It was estimated that
over 500 M. venenosa and 50 E. striates were removed from the spawning
Nemeth, R.S. et al. GCFL57 (2006)
Page 555
aggregation each year. Following these heavy catches, this study found that M.
venenosa did not aggregate to spawn in 2002 but formed a small aggregation in
2003 (n = 50). These data were supported by the fact that fishermen caught
almost no grouper in 2002 and very few in 2003 (RSN Personal observation).
Unfortunately, it was not possible to determine if M. venenosa successfully
spawned in either year. These low numbers,however, strongly suggest that the
M. venenosa spawning aggregation was greatly reduced in this location during
the 2002 and 2003 spawning seasons. Such a rapid reduction in numbers of
fish on spawning aggregations in response to fishing pressure is not unusual
(e.g. E. striatus grouper - Colin 1992, Sadovy and Eklund 1999) but serves to
highlight the need for more responsive management action. In addition to M.
venenosa, E. striates, M. tigris, and M. interstitialis were observed on the
Grammanik Bank. In 2002 small clusters of E. striatus possibly represented
the earliest stages in the re-forming of a spawning aggregation. In March
2003, a single cluster of E. striatus, not previously recorded in either Decem
ber or January, was present on the reef. However, there was no clear evidence
(e.g. behavior, coloration) that E. striatus successfully spawned in 2002 or
2003 at the Grammanik Bank.
In March and April 2004, however, M. venenosa E. striatus,M. tigris, and
M. interstitialis aggregated on the Grammanik Bank in much larger numbers
than the previous two years. M. venenosa formed an aggregation of over 900
individuals. We are unsure why M. venenosa returned in such large numbers
in 2004, but several possibilities exist. There are reports from fishermen that
spawning aggregations of Nassua, yellowfin, and red hind in St. Croix were
known to temporarily relocate to other sites if they received a lot of fishing
pressure during one season (T. Daly Personal communication). For example
the spawning aggregation in 2002 and 2003 may have relocated to an alterna
tive spawning site these years in response to heaving fishing in 2000 and 2001
but returned to their historical spawning site on the Grammanik Bank in 2004.
Recent data for red hind also suggests that this species may have peak
spawning years that occur on a regular two-year cycle (Nemeth 2005). Thus,
2004 could have been a peak year, 2003 a low year and 2002 could have been
a peak but was affected by heavy fishing in the previous two years.
M. tigris and M. interstitialis also formed spawning aggregations of 90
and 25 individuals, respectively. In contrast, E. striatus was observed in
distinct pairs and did not form a larger aggregation (RSN Personal observa
tion). Colin (1992) found that when E. striates was present in large groups of
greater than 500 fish the majority of fish within the spawning aggregation
displayed the bicolor color pattern, whereas when they occurred in small
spawning groups of less than 100 fish only about half were displaying the
bicolor phase. E. striatus were typically observed in loose groupings swim
ming or resting near the reef. We also observed four of 60 E. striatus display
ing the bicolor phase, but only three of these individuals seemed to be paired
with a visibly gravid female. In group spawning species such as E. striatus, it
is not known what minimum population size is needed to initiate group
spawning behaviors, but the minimum aggregation size required to initiate
courtship and spawning in E. striatus may be significantly larger than required
by other haremic groupers such as red hind (E. guttatus) and M. venenosa
Page 556
(Sadovy 2001). Colin (1992) recorded E. striatus in small groups of less than
100 fish which were spawning, but only about half were displaying the bicolor
phase which typically proceeds spawning. He also found that courtship
occurredin groups of only ten fish. An estimated 60 E. striates were counted
on the Grammanik Bank in April 2004, but courtship was seen only once, and
spawning was not observed so it is possible that although an aggregation may
be re-forming there may not yet be any successful spawning.
With the exception ofE. striates, the spawning season of all other grouper
and snapperspecies observed on the Grammanik Bank was consistent with the
reported literature from throughout the Caribbean (Sadovy et al. 1994, Claro
and Lindeman 2003). Nassau typically form spawning aggregations from
December through February, but have been found with ripe ovaries later in the
spring as well (Olsen and LaPlace 1978,Thompson and Munro 1978, Colin et
al. 1987, Colin 1992, Tucker at al. 1993, Sadovy et al. 1994, Claro and
Lindeman 2003). Although E. striatus had previously spawned December
through February in the Virgin Islands (Olsen and LaPlace 1978), spawning
now seems to be following the seasonal pattern of M. venenosa (i.e. February
to April). The seasonal shift could have two possible explanations. The
historical site of the E. striates spawning aggregation was located within the
present boundaries of the red hind Marine Conservation District (Olsen and
LaPlace 1978). Because the population "memory" of this historical aggrega
tion site was lost when the spawning aggregation was fished to extinction in
the late 1970s, the new cohort off. striatus may have followed or copied die
behavioral patterns and migratory routes of M. venenosa and E. striatus is just
now reforming at a different location and season. The second alternative, as
suggested by commercial fishermen, is that there are so many E. striatus at the
historical spawningaggregation site thatthe fish showingup at the Grammanik
Bank are over-flow from the historical spawning aggregation site. This
alternative still needs to be verified.
The meanlength (70.7 cm TL) andF:M sex ratio (1:1.1) ofM. venenosa in
this study was nearly identical to values reported by Thomson and Munro
(1978) for the oceanic banks off Jamaica (mean TL = 68 cm, F:M = 1.2:1).
According to Thomson and Munro (1978), these oceanic banks received
relatively low fishing pressure. The similarity in length frequency and sex
ratio of M. venenosa from unexploited oceanic banks off Jamaica in the mid1970s and St. Thomas in 2004 may indicate that M. venenosa at the Gram
manik Bank may be less impacted by fishing than previously thought. This
would support the hypothesis that the groupers did, in fact, find an alternative
spawning site during the two years when the aggregation did not form on the
Grammanik Bank. Length-frequency data for E. striatus from this study were
also similarto those reported for E. striates in St. Thomas prior to its collapse
and the relativelyunexploited oceanic banks of Jamaica, Belize and Bermuda
(Olsen and LaPlace 1978, Thompson and Munro 1978, Sadovy and Eklund
1999). The length frequency distribution also suggests that the age structure of
E. striatus at the Grammanik Bank is dominated by four to six year old fish
(Olsen and LaPlace 1978). Sex ratios from unexploitedpopulations tend to be
close to unity (Sadovy and Eklund 1999) whereas the female:male sex ratio at
the Grammanik Bank was biased towards females (2.4:1) and similar to
Nemeth, R.S. et al. GCFI:57 (2006)
Page 557
exploited populations in the Cayman Islands (Colinet al. 1987). Although the
length frequency data reflects a size composition from unexploited popula
tions, the biased sex ratio at the Grammanik Bank suggests that E. striatus
continues to be exploited (Sadovy and Eklund 1999) as bycatch during the M.
venenosa spawning aggregation in the Virgin Islands. This pattern may also
indicate that sex ratios are very sensitive to even moderate fishing pressure on
spawning aggregations. Alternatively, these biased sex ratios could also be
present in the size structure of a reforming E. striatus spawning aggregation.
As reforming aggregations have never been documented, this could just be the
natural pattern and the number of males will increase as population size
increases.
Continued fishing pressure on M. venenosa with associated catches of E.
striatus will eliminate the likelihood that this E. striatus will re-form a
spawning aggregation in this location. If fishing is allowed on the Grammanik
Bank, the reestablishment of grouper spawnmg may be disrupted not only by
the removal of individual fish but also by the disruption of complex behavioral
patterns that are required to initiate courtship and spawning. Although the
Grammanik Bank was recommended for closure as early as November 2000,
the Caribbean Fisheries Management Council has only recently approved an
interim seasonal closure of the Grammanik Bank from February through April
2005. Results from this study support the seasonal closure of the Grammanik
Bank from February 1 to April 30, as the time period most likely to protect the
yellowfin grouper spawning aggregations, and more importantly, to provide
protection for a potentially reforming Nassau Grouper spawning aggregation.
Future research will need to address how these commercially important species
utilize the habitats within the Grammanik Bank during the spawning period but
also during the entire spawning season to ensure that movement during
spawning does not go beyond the proposed closure boundaries. Finally, this
study also highlights the fact that the Grammanik Bank may be regionally
important as a multi-species spawning aggregation site and management
measures that suitably protect the spawning populations of several aggregating
species of grouper and snapper that occur at this site from February through
August each year will need to be evaluated.
LITERATURE CITED
Aronson, R.B., P.J. Edmonds, W.F. Precht, D.W. Swanson, and D.R. Levitan.
(1994).
Large-scale, long-term monitoring of Caribbean coral reefs:
simple, quick, inexpensive techniques. Atoll Research Bulletin 421:1-19.
Beets, J. and A. Friedlander. 1992. Stock analysis and management strategies
for red hind, Epinephelus guttatus, in the U.S.V.I. Proceedingsofthe Gulf
& Caribbean Fisheries Institute 42:66-79.
U.S. Virgin Islands. Environmental Biology ofFishes 55:91-98.
Bohnsack, J. (ed.). 1990. The potential of marine fishery reserves for reef fish
management in the US Southern Atlantic. NOAA Technical Memorandum
NMFS-SEFC-261.14 pp.
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Claro, R. and K.C. Lindeman. 2003. Spawning aggregation sites of snapper
and grouper species (Lutjanidae and Serranidae) on the insular shelf of
Cuba. Gulf & Caribbean Research 14:91-106.
Colin, P.L., D.Y. Shapiro, and D. Weiler. 1987. Aspects of the reproduction of
two species of groupers, Epinephelus guttatus and E. striatus in the West
Indies. Bulletin ofMarineScience 40:220-230.
Colin, P.L. 1992. Reproduction of the Nassau grouper, Epinephelus striates,
(Pisces: Serranidae) and its relationship to environmental condition.
Environmental Biology ofFishes 34:357-377.
Nemeth, R.S. 2005. Population characteristics of a recovering US Virgin
Islands red hind spawning aggregation following protection. Marine
Ecology Progress Series 286:81-97.
Nemeth, R.S. and A. Quandt. 2005. Differences in fish assemblage structure
following the establishment of the Marine Conservation District, St.
Thomas, US Virgin Islands. Proceedings of the Gulf and Caribbean
Fisheries Institute 56:367-382.
Olsen D.A. and J.A. LaPlace. 1978. A study of a Virgin Islands grouper
fishery based on a breeding aggregation. Proceedings of the Gulf and
Sadovy, Y. 1996. Reproduction of reef fishes. Pages 15-59 in: N.V.C. Polunin
and CM. Roberts (eds.). Reef Fisheries. Chapman and Hall, London,
England.
Sadovy,Y. 2001. The threat of fishingto highly fecund fishes.Journal ofFish
Biology 59:90-108.
Sadovy, Y. and A. Eklund. 1999. Synopsis of biological data on the Nassau
grouper Epinephelus striatus (Bloch. 1792), and the jewfish E. itajara
(Lichtenstein, 1822). NOAA Tech. Rep. NMFS 146 and FAO Fish.
Synop. 157.
Sadovy, Y., P.L. Colin, P.L., and M. Domeier. 1994. Aggregations and
spawning in the tiger grouper, Mycteroperca tigris, (Pisces: Serranidae).
Copeia 1994:511-516.
Thomson, R. and J.L. Munroe. 1978. Aspects o fthe biology and ecology of
Biology 36:115-146.
Tucker, J.W., P.G. Bush, P.G., and S.T. Slaybaugh. 1993. Reproductive
patterns of Cayman Islands Nassau grouper (Epinephelus striatus)
populations. BulletinofMarineScience 542:961-969.

Caribbean Spawning Aggregations: Biology and Management Status

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