GROUNDFISH SURVEYS IN TUE ATL~TICIBE~`YATERS (ICES

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Cl\119971Y:08
Theme Session on :
Synthesis and Critlcal Evalüation of Research Surveys (Y)
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GROUNDFISH SURVEYS IN TUE ATL~TICIBE~ 'YATERS (ICES
DIVISIONS VIIlC AND IXA): IIISTORY AND PERSPECTIVES
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Cardador, F. , Sanchez, F. ,Perelro, F.J. ,Borges; l\1~F. ,Caramelo, A.l\I. ;Azevedo,
1\1. 1, siiva A. 1, Perez, N. 3, l\Iartins, l\I.~I. 1, 01a80, 1. 2, Pestana, G. 1; Trujillo, V. 3 and
Fernandei, A4.
Instituto de Investiga'räo das Pescas e do Mar (IPIMAR), Av. Brasflia. 1400 Lisboa. Portugal
Instituto Espanol de Oceanografia (IEO), Centro Ocenogräfico de Santarider, Apto 240 39080, Santander, Spain
3 Instituto Espanol de Oceanografia (lEO), San Miguel de Oya. Apartado 1552, Cabo Estay, Vigo, Spain
4 Instituto Espanol de Oceanografia (lEO), Av. deI Brasil 31 28020, Madrid, Spam
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,ABSTRACT
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Spanish Oceanogrnphic Institute (IEO) and Portuguese Research lristitute {lPIMAR, ex-INIP)
using their research vessels "Comide de Saavedra" and ''Noruega'' have conducted grorindfish
surveys in SpaIiish arid Portuguese waters. The resultS ofthese surveys have been reported to the
relevant ICES Working Groups, communicated to ICES An11ual Comerences arid/or published
injoUrriaIs ofbioio gy arid flsheries. Data coIlected from gfoundfish surveys were also the basis
to carry out assemblage studies and to severaI advices to the Spamsh, Poittiguese and Etiropean
fishery administrations concef?ing the impleinentiltion of technicai measures for fish stock
management. This communicatiori iritendS to give irifonnation about the PaSt, the present and the
future of these stirveys, concerning objecÜves, methodology and publications. Critical aspectS
and solutions to improve some aspects are presented.
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INTRODUCTION
The Iberirin area corresponding to ICES Divisions VIIIc and IXa have been intensively
investigated during the last two decricles using inforinaiion provided by groundfish stirveys.
The Oceanographic Institute (lEG), Spaln and Research IrisÜciite (iPIMAR; ex-INIP), Portugal
using the Spanish research vesseI Cornide de Saavedra and the Portuguese research vessel
Noruega initiated growidfish stirveys research in AtlanHc Iberian waters in 1974 arid in 1979,
respectively, covering the \vaters under the corresponding national jurisdiction.
The estiIIlätion ofthe abundal1ce and the st11dy of distribution ofthe most important comniercial
species iri the area are common objectives. The resultS provided by these groundfish surVeys ruive
been extremely useful to assess and monitor the state ofthe stocks under routine assessment in
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ICES and other commercial important fish stocks in the area. This communication intends to
give information about the use of these surveys, in the past, the present and concerning
objectives, methodology and derived publications. Critical aspects and solutions to improve
methodologies and further use ofthese survey series are discussed.
I. GROUNDFISH SURVEYS CURRENT OBJECTIVES
Area Covered
Each national Institute investigated the areas under national jurisdiction. Figure I indicates the
areas surveyed and the corresponding ICES Divisions VIIIc and IXa.
1. Division VIIIc ( Cantabrian Sea) and Division IXa (Galician waters and Spanish waters
of the Gulf of Cadiz )
Spanish surveys
The main objectives ofthe Spanish surveys are:
- to estimate the relative abundance ofthe main fish, crustacean and cephalopod populations;
- to describe the spatial distribution pattern ofthe species;
- to estimate the year dass strength of selected species (mainly hake);
- to gather data for the determination ofbiological parameters, including feeding and growth.
The target species in the Northern Spanish surveys are: hake (Aferluecius merluecius), blue
whiting (Afieromesistius poutassou), megrims (Lepidorhombus boscii and L. whiffiagonis),
monkfish (Lophius budegassa and L. piseatorius), horse mackerel (Traehurus traehurus land
Norway lobster (Nephrops nor\.'egieus). The target species in the GulfofCadiz surveys are: hake,
wegde sole (Dieologoglossa euneata), horse mackerei, Spanish mackerel (Seomber japonieus),
Seabreams, prawn (Penaeus kerathurus), shrimp (Parapenaeus longirostris), octopus (Oetopus
vulgaris and Eledone mosehata) and Cuttle fish (Sepia officinalis).
2. Divisions IXa (Portuguese waters)
Portuguese surveys
The target species ofthese surveys are hake, horse mackerei, mackerei, blue whiting, megrims,
monkfish and Norway lobster.
The main objectives ofthe Portuguese groundfish surveys are:
-to estimate indices ofabundance and indices ofbiomass ofthe most important fish species off
the Portuguese continental waters;
-to study the distribution pattern and estimate indices of abundance for recruits;
-to estimate biological parameters, maturity evolution, sex-ratio, weight, food habits;.
-to build length and/or age compositions for the target species.
Furthermore, complete species list is provided and information on the length distribution of other
commercial species is available.
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The indices of abundance together \vith its age structure allow to assess the state of the stocks
when integräting this information in analytical assessments. They are also used for monhoring
the state ofthe stocks with incomph~te iriformation to perfomi a fuH analytical assessment.
11. GROUNDFISH SURVEYS HISTORY
1. Spanish surveys
The Spanish Oceanographic Institute (IEO) has been carrying out bottom trawl surveys since
1974. In the begining, the area, time ofthe year, the objectives and consequently the sampling
design ofthe surveys was different to the present one. Ums, during 1974-i979, bottorn trawl
surveys were accomplished in waters of Galicia (IXa Divisions North and West Villc) in
different months ofthe year Üv1ay -September), being the mall objective the distribution of!he
commercial interest resomees as weH aS the assoeiated fauna. Fishing stations were alloeated at
radials perpendieUlar to the coast rind at different deptbs.
From 1980 on \varcls, based on the available information ofthe previous surveys, it was decided
to eariy out arandoin stratiried sampling iri Autumn. The main criterio~ for the sti-atificarlon was
the distribution ofrecruits ofhake in the area, which was th6 primar)r objective ofthese surveys.
In 1983 the sampling eoverage was enlarged ineluding the whole VIIIc Division (Cantabrian
sea) and, simultaneously the sampling design, the eha.meteristies ofthe gear and the duration of
the haul were established for the AutunUi siirveys. BetWeen 1984 rind 1988, ci senes of Spring
stirveys were made in the same area and foHowing the same methodology in order to
complement the information on the annual eyCle of the speeies. The Spring series finlshed in
1988 but the AutWiui senes have been maintained up to the preseni.
Since 1993 a new series of sUrveys was initiateci in the South Atlantic region of the Iberian
Penirisula (Gulf of Cadiz) using the same, sampÜng methodology as the one used in Autumn
groundfish surveys eovering the North ofSpain. This new series eompletes the eoverage ofthe
whole Iberia Atlantie waters, from the Cantabrian Sea to the Strait of Gibraltar (lCm; Divisions
VIlIc aitd IXa ).
FoIioWing the reeoinniendatiori ofthe ICES Stlidy Group on Bottorn Trawl Surveys in Sub-areas
VI,VII and vm and Division IXa (Anon 1991b), during the 1992 sUiveya caÜbration look place
on board of RN Cornide de Saavedra with the bakri gear and the French RN 11zalassa With the
stiindrird gear system GOV 36/47. Th~ catch efficiency and the conversion,eoefficierits for the
different species were obtained (Sänchez, Poulard rind De la Gandara, 1994; Anon, 1994a).
2. Portuguese surveys
Portuguese grouridfish surveys have been eondueted along the PortiIguese coritinentai waters
(Figure 2 ) sinee June 1979 on board ofthe RN Noruega. Initially the main objectives ofthe
sUrveys were to estimate the abundance rind study the distribution of the most importmt
corririlercial species iri the Portuguese trawl fishery: hake, horse mackerei, blue whiting,
seabrearns and NorWaY lobster. Reeruitinent indices ofaburidance and distribution for hake, arid
horse mackerel were also evali.mted in the AutWnri surveys. Additionally, trawl selectivity
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experiments for hake and horse mackerel with 40 mm mesh size, were also conducted during
1981 surveys using the covered cod-end method.
A stratified random sampling design was adopted during 1979-1989. The number of strata
changed during this period: from 1979 to 1980 the surveyed area was divided into 15 strata and
since 1981 into 36 strata. Based in the statistical analysis ofthe previouS surveys the design was
revised in order to decrease the variance within stratum. The new strata are smaller than the
previous ones and can be combined to get the older ones. The aim of increasing the number of
strata was to increase the probability of spreadiDg the rimdom sampled units in order to decrease
the total variance ofthe meari abundance indices by species.
The boundaries of each stratum are based on depth and geographical areaS. The depth ranges
during 1979-1988 were 20-1 OOm, 10I-200m and 201-500m. Each stratum was divided into unici
of approximate1y 25 nm2, sequentially numbered. During 1979-1980 the riumber of random
hauls per stratum was based on the previous infonnation ofthe relative abwidance ofthe target
species in each geographical area and on the vessel time available. During 1981-1989, when the
number of strata was 36, two random units were sampled by stratwn whenever possible, to
become possible to estimate the standrird error ofthe stratified mean by stratum.
The tow duration was 60 minutes during 1979-1985 at a trawling speed of3.5 KIlots, changing to
30 minutes during 1986-1988, and changed again to 60 minutes since 1989, maintaining the same
trawling speed. The decrease from 60 to 30 minutes was based on ari anrilysis which has indicate
that a 30 minutes tow was enough to gei abund3nce indices for the target species (Cardador,
1983b). However in the 1989 Summer survey, experiments with the two durations at the
trawling speed of 3.5 Knots have been perfonned indicating timt 60 minutes tow was more
adequate to sampie aII the structure ofthe horse mackerel population. The large adults ofhorse
mackerei were not caught at a trawling speed of3.5 knotS with a duration of30 rriiriutes because
the large pelagic fish can swim at at higher speedS in front ofthe trawl nel. It is by mantairiing
the trawl ptirsuing the fish during a longer period than 30 minutes that the larger horse mackerel
looses its stamino and enters into the traw nel. The juveniles wen: weil sampled with 30 minutes
trawling at 3.5 knots.
Finally in Autumn 1989 a fIXed stations plan was established as a result of an extensive
discussion on the scope ofICES Methods Working Group (leES, 1989, i990) about the trade
on biased estimations with low variance (flxed design) or tinbiased estimations with large variance
(stratifled design). The fixed design is more appropriate for a time series obtairied for the purpose
of tuning the commercial catch-at-age time series. As a result it was considered that the fIXed
station design is more appropriate for VPA tuning than the random allocation design.
Simultaneously the survey area was extended to the 750 m bathymetrlc in order to sampie the
adult hake, and the lower distribution bound ofNorway lobster and monkfish (see details ofthe
methodology on techlUcal description below).
Ouring the period 1979-1996 a total of36 surveys were carried out. The season, total fishing days
and valid hauls by survey are shown in the Table 1. In average 2 surveys per year were carried
out, with 21 effective fishing days and 90 valid hauls per survey.
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Dunng 1990~1994 and under FAR project MA- 1-203\ the second aim of the surVeys was to
estimate the abundance arid distribution of eggs arid larvaecif the commercial species. A
sampling scheme with a grid of92 stations was applied. The statioris were settIed at 22 east-west
sampling transeptS, 20 nautical mHes apart, with depths varying from 20 to 1000 m. The
sarnpling stations were placed S'and 10'apart from each other in order to fit the bottom
topographY. Plankton sarnples were collectedwith a Bongo net (60 cni ofmouth cliamei~r and
33SIlm and SOS11m mesh size), by oblique luiuls from the surface to a maximum depth of200 m
or to the depth of seabed. These stations were conducted during the night. Using
(Conductivity, Temperature arid Depth recorder"Sea-Bird" (Model Seacat SBE 19) the
terriperature and salinitity profiles were obtained at each plankton station. This is pärti6Uiar
important to monitor the presence ofthe thermocline for sampling strategy. At its presence the
eggs of mackerel arid horse mackerel are dishibuted above the therrnocline.
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111. TECHNICAL DESCRIPTION
1. Spanish sunreys
siti p and gear characteristics
Spanish surveys cover the ICES Divisions VIIIc and part of Division Dca (Cantabrian sea; off
Oalicia and Gulf of Cadiz, Figure 2). All siuveys were camed out with the Sparnsh RN Cornide
de Saavet{rd. This stern trawler was trimsfonned in 1984 from itS original 56 ni (LL) arid 990
ORT to 67 In (LL), 1133 GRT and 16S0 KW.
The gear used is aBaka trawl (a commonly used gear in the Spanish trawl fleet) \vith a 43.6 m
footroPe arid a 60.1 headline which had a cod-end of20 mm mesh size. In the most recent survey
headline height and wingend were measured using Scänffiar, arid values of 1.9 m and 22.0 m
\vere obtairied respecrlvely. Up to 1985, a codencl cover of20 mm mesh
used and sirice then
a 20 m:rii mesh codend liner has been adopted.
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Sampling desigit hi Spanish urea
A straiified random sampling scheine has been adopted. The stirvey area has been stratifled
according to depth and geographical criteria arid. In the Nofth ofSpaln S geographical sectors
and tlrree depth zones have been used (30-100, 101-200, 201-S00 m) (Figure 2). Iri the Gulfof
Cadiz, the shelf ancl slope waters were divfded into five depth strata (15-30, 31-100, 101-200,
20i-soo and 501-700). All strata are divicled into urntS of2S square nautical mHes (SxS). The
total number of hauls is determmed by the ship tinie assigned to each stirvey resuliing in a
covernge of one haul per SO nni2 (120 hauls per stirvey in the Noith siIrveys, approxima.tely 20
hauls per ICES rectangle). Thc nUmbe~ ofhauls per strata is proportional to the trawlable area
and its allociitions are random selected.
Trawling is carried out durlng dayÜght. In the North of Spahi, tows had one houl- duration in aIi
"Estimation of the abUIldance arid study of the distribution pattern of hake, horse
mackerei, mackerei; monkfish arid niegrim in leES Div. IXa (Portuguese waters)"
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surveys before 1984, and were reduced to 30 minutes thereafter. In the Gulf of Cadiz the haul
duration is one hour. In both surveys towing is camed out at a speed of 3 knots. Starting time of
the hau! is defined when winches stop and the endmg time when the pull back ofthe net starts.
Information collected and database
The log sheet and the number and \veight of all species caught are included in the surveys
database, as weIl as the size distributions of all the fishes and of the invertebrates of commercial
interest. All the survey data are processed on board using a software package specifically created
for it (files in dBase III format) and with the possibility to generate the file formats for records
types 1,2 and j offfiTS data. Salinity and temperature by depth are recorded at the end ofeach
fishing station tising a CTD probe.
Results
The estimation of abundarice indices and its statistical dispersion are obtained following a
random stratified sampling protocol (Cochran, 1966).The minimum biomass by species is
obtained applying the swept area method. Data are processed for the catches (in weight and in
number) and by length class or/and by age group for each species. The age/length keys (ALK)
are derived from otolith or other hard parts readings or by indirect methods from species length
composition.
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Abundance and distribution patterns of some target species have been investigated to detect
factors that could cause its variability during the different surveys. Special attention have been
given to studies on hake recruitment indices. Based on previous studies the geostatistie tools
are used to investigate age group 0 aggregations of hake and its strategy of occupation of the
nursenes.
Oceanographie stations are carried out usmg CID SBE-25 equipment, in order to get an uniform
and representative coverage on a spacial and temporal scale. Hydrographie stations are performed
at the end of each fishing haul and CID profiles from the shelf edge to the oceanie area are
completed during the night. The areas which were not covered with the fishing stations CID
profile are covered with extra hydrographie stations. To analyse the dynamics of mesoscale and
the vertical motion associated, the methodology of objective spatial analysis is applied,
separating the macroscale and mesoscale contribution to the total field. To study the vertical
motion the formulation ofthe Q vector in the equation omega (Hoskins ct al. 1978) is used.
2. Portuguese surveys
Ship and gear characteristics
Portuguese surveys were carried out on board ofthe Portuguese RIV Noruega, a stern trawler
with 47.5 m length overall, 495 tons GRT and 1500 HP, built in 1978 in Bergen, Norway.
The trawl gear used is denominated Norwegian CampeIl Trawl 1800/96 (NCT). The main
characteristics ofthis gear are the ground rope with bobbins, 9 m sweep and three bridles, lower
40 m, and upper and middle 20 m long. During 1979-1980 a codend of 40 mm mesh size was
used. Selectivity studies conducted during 1981 groundfish surveys were made with a cover of
20 mm and a codend of 40 mm mesh. Sinee 1982 a single codend of 20 mm mesh size is
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adopted. The mean vertical opening is 4.6 m arid the mean horizontal operiing be~veen wings and
doors are 15.1 m and 45.7 rri, respectiveIY. These geai- parameters were obtmned with Scammir
Equipment. The polyvalent trawl doors used are rectangUlar (2.7 mx 1.58 m) \vith ai:i area of
3.75 m~ and weighiing 650 Kg.
Sampling design
Surveys cover the Portugtiese coniinentai \vaters from 20 m to 750 in; follo\ving a fixed station
sampling scheme. A total of 97 flXed stations are planned, spread over 12 sectors. Each sector
is subdivided into 4 depth ranges: 20-100m, 101-200m, 201-500rit arid 501-750 m, with atotal
of 48 strata (Figure 3). The positionS ofthe 97 fiXed stations \vere selected based on coriimon
stations made during 1981-1989 surveys and triking irito account ihat two stations shöUld be
made by stratum. A maximum of 30 supplemeritary stations are planned, fixed in each season,
to be carried out if ship time is available 01' to replace positions that due to particulai' factofS
not possible to accomplish.
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Fishing stationS take place during daylighi, \vifu an average duration tow of 60 minutes with a
mean trawl speed of3.5 knots.
OceanograpWc stations take place at the [mal of each fisrung station using a CTn equipment in
order to get temperature and salinity clata by depth to be used in biological studies.
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Information collected and database
The catch from each hau! is sorted arid \veighed by speCies. F 01' the target species and for some
other commercial species (fishes, cephaiopods arid crustaceaiis) length measureritents, as well
as other biological informatiori, e.g., weight by length group, sex, mattirity stages, collection of
otoliths, stornach contents, are undertaken.
Iri 1990, a database was created at IPIMAR dWirig the FAR project MA.1.203 using a SQL
relational database iri PC-DOS system (software Rbase 2.0 later upgraded to Rbase 4.0).
Recently, t.his database was transferred to a \viridows environment using Microsoft Access 2.0.
ThI-ee main tables, one containing the log sheet (hau! iliformation, positions, etc) other containing
species sheet (catch data) and the ihird contairiirig sarnpie length distribution, are part ofthis
database. Maturity stages, individUal weigh, otoliths are stored iri independent tables for each
species. An accessory table containirig scieritific and common names arid the three FAG letter
codes for the species waS also adopted.
Scientific effort
The hUriiari resources at sea involve 4 flshery biologist and 7 technicians per surVey. The data are
recorded in the database on board at the end of each fishing station.
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IV. USE OF SURVEY INFORl\lATION
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The Sparush and Portuguese groundfish slirveys data have beeri the mairi source for several
bioiogical studies and stock parameters estimation. These studies include those related to the
species distribution by area and depth, lengili-weight relationship, age determination, matiirlty,
fecundity, food habits, recruitrrient estimation, abimdarice indices and cpue trend analysis.
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Table 2 summarizes the referred studies by species. Most of the results of these studies are
reported or published as is indicated in item 5. Data collected from groundfish surveys were also
the basis to carry out assemblage studies on the Portuguese and Spanish shelf and to establish
fishing closed areas as in the case ofhake (STCF, 1990).
Ichtyoplankton studies were also performed during 1990 - 1994 under the Portuguese FAR
project MA 1203, to estimate the abundance and distribution of eggs and larvae of the most
commercial species.
Summer and Autumn Portuguese series as weIl as Autumn Spanish series have been used for
stock aSsessment (VPA tuning) as it is shown in Table 3.
Vo RESULTING PUßLICATIONS AND REPORTS
Most of the results provided by the groundfish surveys are reported to the relevant ICES
\Vorking Groups, coinmimicated to ICES Annual Conferences and/or published injoiunals of
biology and fisherieso
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Data collected from groundfish surveys were also the basis to carry out assemblage studies and
to several advices to the Spanish, Portuguese ?nd European fishery administrations conceming
the implementation of technical measures for fish stock management.
The main resulting puhlicaiions and reports are listed helow:
1. Spanish publications
Abaunza. P., 19950 The use of larval Anisakis simplex (Nematoda: Ascaridoidea) infection
patterns can improve our hiological knowledge ofhorse mackerel, Trachurus trachurus, from
Cantabrian Sea and Galician \vaters (lCES DivisionS VIIIc and IXa). Working Document to the
1995 ICES \Vorking Group on the Assessrrient of Mackerei, Horse mackerei, Sardine and
Anchovy.
Abaunza, Po,. Farifia, A.C and Carrera P., 1995. Geographic variations in sexUal maturity ofthe
horse mackerei, Trachurus trachurus, in the Galician and Cantabrian shelf. Seientia Afarina.,
59(3-4): 211-222.
Abaunz~ P., Villamor, B. and. Perez, Jo R., 1995. Infestation by larvae of Anisakis simplex
(Nematoda: Ascaridata) in horse mackerei, Trachurus trachurus, and Atlantic mackerei, Scomber
scombrus, in ICES Divisions VIIIb, VIIIc and IXa (N-NW ofSpain). Seientia Afarina., 59(3-4):
223-233.
AstudiIIo, A. and Sanchez F., 1989. Selectividad de las artes de arrastre para el gallo
(Lepidorhombus sp. ) en aguas del Cantabrico. In! Tec. Inst. Esp. Oceanogr. 72: 27 pp.
De La Gandara, F.,. Rodriguez-Cabello, C. y Sanchez, F., 1995. La Pintarroja (Scyliorhinus
canicula L.) en los fondos arrastrables deI Cantäbrico. Actas IV Col.lnt.Oceanog,.. Golfo de
Vizcaya,31-38.
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Farifia A.C., F.J. Pereiro and A. Fernand~z 1985. Peces de los fondos de arrastre de la Plataforimi
contiriental de Galicia. Bol. Inst. Esp. Oceanogr. 2(3) 89-98.
Faniia, A.C., J. Freire and E. Gonzalez-Gurriaran. 1994. Nephrops norvegicus iri the Galician
continental shelf(NW Spain): Abundance and distribution. Fish. Res. 19:333-347.
Fariiia, A.C. and F.J; Perdro. 1995. Distribution arid a,bundarice of moliuSc and decapod
cnisciceans. iri trawl sampIes from the Galician Shelf (NW Spain). ICES mar. Sei. Symp.
199:189-199.
Freire, J., E. Gonzalez-Gurriaran and I. Dlaso, 1992. Spatlal Distribution of Afunida intermedia
and Al. sarsi (Crustacea:Anomura) on the Galiciari Continental Shdf(NW Spain): Applicationof
Geostatistical Analysis. Estuarine, Coastal and ShelfScience 35,637-648.
Freire, J., E. GOnzalez-Gurriaran, I. Dlaso and L. Fernandez, 1991. AnaIisis geoestadistico de ia
distribuci6n espacial de Plesionika heterocarpus y Solenocera '!1embranacea (CiuSuicea:
Decapoda) en la plataforma continental de GaIicia. Bol. Inst. Es[J. Ocetinogr., 7(2): 79-88.
Garcia-Castrillo, G. and I.Dlaso, 1990. Composition and strUctrire of the. invertebrntes
megaberithos in the platform ofthe Cantabrian Sea. ICES SHELL SYAfP. N°51:7 p.
Garcia-Castrillo, G. and I. DlaSo, 1995. Composition arid strUcture of the invertebrate
megabenthos on the shdf of the Cantabnan Sea. ICES Mar. Sei. Symp. Vo1.199: 151-156.
Gil,1. 1995. Circulaci6n e hid.rogriifia en ia campma DEMERSALES 0993. Eri: Actas dei IV
Coloquio InternaCional de Oceanografia dei Golfo de Vizcaya. Ed. D. Cendrero e I. Dlaso,
Santarider: 275-279.
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Gonzilez, R.; Dlaso, I. and Pereda, P., 1985. Contribuci6n al conocimieritci de Ia alimeritaci6n
de la merliIza (Merluccius merluccius L.) en laplataforma continental de Galicia y deI
Canmbrico. Bol. Inst. Esp. Oceanog., 2(3). 1985, 49-60.
Gonialez-Gurriaran, E. and i. oiaso, 1987. Cambios espaciales y temporales de los crustaceos
decapodos de Ia phitaforma continerital de Galicia (NW de Espana). lmi.Pesq.VoI.51.SupI.1 :323341.
Jimenez, M.P.; I. Sobrino and F. R3.rD.os 1997. Distribution pattern, reproductive biology and
fishery ofwedge sole Dicologoglossa cuneata ([de Ia Pylaie] Moreua 1881) in the GuifofC diz
(S.W. Spain). Afarine Biology (in press).
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Larich J., Pifieiro, C. and Perez, N., 1996. Megrim (Lepidorhombus whiffiagonis) gfoivth pattern
in northeast Atlantic. Fisheries Research. 26: 279-294.
Landri, J. and Perez, N., 1997. Ageing ;on sight' of four spot megrim, Lepidorhonibus boscii
(Risso) otolithS arid their validation. Fisheries Research. 30: 27-31.
Larlda, J. arid Perecia, P. 1997. Notes on the gi-oWth ofWhite Monkfish (Lophius piscatoriuS, 1..)
in the Northerri Spanish conthlental shelf (lCES Divisions VllIc and IXa). lCES
1997/CC:07, 9 pp.
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Meixide, M., P. Carrera, F. Sanchez and C. Porteiro 1991. Distribution of horse mackerel
(Trachurus trachurus L.) in the North-Atlantic waters ofthe lberian Peninsula. MackereUHorse
Mackerei Egg Production Workshop. \Vork Docum.
Olaso, 1., 1990. Relacion entre Ia fauna demersal yel bentos. En: Oceanograf(a dei Golfo de
Vizcaya vrn Cursos de verano de San Sebastian JED. Urrutia y Rallo), 63-92. Univ. Pais Vasco,
San Sebastian.
Olaso, 1., 1990. Las pesquerias demersales dei Mar Cantäbrico. En: Oceanografia dei Golfo de
Vizcaya, vrn Cursos de verano en San Sebastüin JEd. Urrutia y Rallo), 345-368. Univ. Pais
Vasco, San Sebastian.
Olaso, 1., 1990. Distribuci6n y abundancia dei megabentos invertebrado en fondos de la
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Borges, M.F., Silva, A., Abaunza, P., Eltink, A., Lucio, P., \Valsh, M., Poulard, J.C., Casey, J.,
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Azevedo, M., 1994. Biological and fishery data synthesis for the southem monkfish stocks.
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...
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Borges, M.F., 1986. Design arid aßalysis oftrnwl siuveys for estirriatimg horse biomass indices
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Borges, M.F. and Gordo, L.S., 1991. Spatial distribution by season and some biological
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Borges, M.F., Turner, R.J. arid Casey, J.; 1993. Plasma tranSferrin polymorphysms in scad
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Cardador, F. and Borges, M.F., 1982. Mesh selection ofHake (Merluccius merluccius) and Horse
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Cardador, F., 1986. New experiments an trawl-mesh selection ofhake on the portuguese coast.
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Cardador, F., 1988. Estrategias de explora9äo do Stock de Pescada (Merluccius inerluccius L.)
das äguas Ibero-Atl5.nticas. Efeitos em stocks associados. INIP, Dissertar;äo original para
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\Vorking Doc. to the Southern Hake Task Force Meeting. IPlMAR, 10-14 Oetober, 1994, 2pp.
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Cardador, F., Silva, A., Pestana, G.; Mrirtins, M., Borges, M.F.; Azevedo, M.; MuIta, A..,
Caramelo,A;, Faiinha, A., AforiSo, H. imd Lopes, P., 1995. "Estimation ofthe abundance and
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Cardador, F. arid Azevedo, M., 1995. A fIrst attempt to compare fIshing emcieney ofthree
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Cardador, F. and Pestana, G., 1995. Abundanee and distribution patteni cif Rock flsh
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"NORUEGA" Jußho 79. Relat.Tee. Adm., lNIP, Lisboa (4), 1980, 132 p., il.
INIP, 1981. Estudo dos recursos demersais da costa portuguesa. 28 Campanha - (N/020 111079),
NIE "NORUEGÄ." OutubrolNovembro 1979. Relat. INIP, Lisboa (2), 1981, 110 p., il.
INIP, 1981. Relat6rio do cruzeiro "tipo demersal" 020130380, realizado a bordo do navio
"Noruega" de 5 a 17 de Mar90 de 1980.Resultadas da pesca. Rel.INIP, Lisboa (4) 1981,116 p.il.
INIP, 1982. Estudo dos recursos demersais da costa portuguesa. Relat6rio da 38 Campanha (N/020 160580), NIE ''NORUEGA'' Maio/Junho 1980. Relat. INIP, Lisboa (13), Junho 1982, 116
p., il.
Martins M. M. and Cardador F., 1996. Abundance and distribution pattern ofSpanish Mackerel
(Scomber japonieus) and Mackerel (Seomber scombrus) in the Portuguese continental waters
(lCES DIV. IXa). ICES Doc. C.M.. H:24, 21pp.
Martins M. M., 1996. New biological data on growth and maturity of Spanish Mackerel
(Scomber japonieus) off the Portuguese coast (lCES Division IX a). ICES C. M. H:23, 17 pp.
•
Moreno, A., 1993. Preliminary study on biological characters of Alloteuthis subulata and
distribution ofthe genus Alloteuthis (Cephalopoda: Loliginidae) in Portuguese waters.ICES .
C.M.1993/K:36.
Moreno, A., Morais da Cunha, M.M. e Pereira, J.M.F., 1994. Population biology ofveined squid
(Loligo jorbesi) and European squid (Loligo vulgaris) from the Portuguese coast. Fish. Res.
21:71-86.
Moreno, A., 1995. Aspectos da biologia de Alloteuthis subulata e distribui9äo de Alloteuthis spp.
(Cephalopoda: Loliginidae) nas aguas portuguesas. Relat. Cient. Tee. lnst. Port. lnvest. Afari.,
8, 16pp.
Moreno, A., J.M.F. Pereira e M.M. Cunha, 1996. Age and growth ofthe squid Loligo vulgaris
from the Portugese Coast. lCES C.M. 1996/K:14.
Murta, A.G., 1992. Ecologia alimentar da Sarda, Scomber seombrus Linnaeus, 1758 e da
Carapau, Traehurus traehurus (Linnaeus, 1758) na costa portuguesa. Relat6rio de estagio
profissionalizante da Licenciatura em Recursos Faunisticos e Ambiente. Faculdade de Ciencias
da Universidade de Lisboa e INIP, 129 pp, 1 anexo e 2 tab.
Murta, A.G., Borges, M.F. and Cabral, H., 1993. Analysis ofstomachcontents ofhorse mackerel
and mackerel in the Portuguese waters (Division IXa) 1990-1992. ICES Doc. C.M.1993/H:39,
16 pp.
Murta, A., Cabral, H. and Borges, F., 1994. Alimenta9äo do carapau na Costa Portuguesa Poster
presented to the 1st Symposium on the Atlantie Iberian Continental Afargin, 28-30 November,
.\{useu Naeional de Historia Natural (University 0/Lisbon).
-18 -
•
Murta, A.G. and Borges, M.F.; 1994.
Factors affecting the abundance eÜstribution of horse
niackerel TraehurUs traehul-us (LinnaeuS, 1758) in the portuguese waters. ICES Doc.
C.M.1994/H:20, 16pp.
Murta, A.G., Borges M.F. and Silveiro M. L., 1995.Infestation of the Horse Mackerei,
Traehurus traehurus (L.), by Anisalds simplex (Rudolphi, 19(9) (Neniatodri, Ascaridida) larirae
in Portugilese waters (ICES Div. IXa).ICES CM 1995/H
Murta, A. G. arid Borges, M.F.; 1996. Morphological variations in the sagitta otoliths ofhorse
mäckerel (TraehuTus traehurus L) in Portuguese waters.ICES. CM 1996/H:27.
SeITäo, E.; 1989.. Comunidades exploradris por arrasto demersal na plataforma contIDental
portuguesa.lNIP, Faculdride de Ciencias de Lisboa. Relat6rio de esmgio de Licericiatirra, 180 pp.
•
Silva, A., 1992. Distribution arid abundarice of John Dory (Zeus laber, Linnaeus 1758) in the
Portuguese continental waters (lCES Div. IXa) during 1986-1991; ICES Doc. C.M; 19921G:68,
33pp.
Silva. A., 1992. Preliminaiy data four-spotted megrim (Lepidorhombus boscii) and megrim
(Lepidorhombus whifjiagonis ) from portuguese groundfish surveys. \VD to 1992 ICES \Vorking
Group on the aSsessment of Southem Demersal Stocks, 18pp.
from
the portuguese
Silva. A.; 1993. Prelimiilarydata Oh NOlway Lobster (Nephrops norvegieus)
groundfish surveys. \VD to 1993 ICES \Vorking Group on Nephrops and Pandalus stocks, 16pp.
Silva, A., 1994. Biologia e Pesca dos Areeiros, LepidorhombüS boscH arid L. whijJiagonis.
Sintese dos conhecimentos acttiais. Relat. Cient. Tee. Inst. Port. invest. Afarit., 1, 40pp.
Silv~ A. and Azevedo, M., 1995. Abtindarice and distribution ofmegrims, Lepidorhombzis boseii
and L whijJiagonis, in ICES Division IXa (Porhiguese waters).Bol. IPIAfAR, 1: 65-77
•
Silva, A., 1995. Feeding habitats of John Dory, Zeuslaber (Linnaeus, 1758) offthe Portuguese
Continental Coast. ICES C.M. 1995/G:17, 18 pp.
Vasconcelos, M.S.L.C.O., 1992. Contribui9öes para 0 estudo da pescaria artesarial costerra e chi
avalia9äo da stock de Faneca, Trisopterus luseus (Limiaeus, 1758) na Costri Contmental
Portuguesa.lNIP, Lisboa, Tese de Licenciattira da Universidade Agostinll6 Neto - Angola, F.C.
de Luarida, Dep. Biologia, 162 pp.
4~ ICES and STCF 'Vorkiog Group Repol1s using data from groundflsh sUrVcys
Anori., 1989. Report ofthe Study GrOlip on reciuitment Indices ofHake from the Southem Stock.
ICES Doc. C.M.1989/G:2, 37 pp.
Arion., 1981. Report ofthe \Vorkmg Group on the assessment ofthe stocks ofhake. ICES CM
1981/G:l1
-19 -
Anon., 1982. Report ofthe Working Group on the assessment ofthe stocks ofhake. ICES CM
1982/ Assess:14
Anon.,1983. Report ofthe Working Group on the assessment ofthe stocks ofhake. ICES CAf
1983 1Assess: 20.
Anon., 1986. Report ofthe Working Group on the assessment ofthe stocks ofhake. ICES CM
19861Assess: 1.
Anon., 1987. Report ofthe Working Group on the assessment ofthe stocks ofhake. ICES CM
19871Assess: 1.
Anon., 1988. Report ofthe Working Group on the assessment ofthe stocks ofhake. ICES CAf
19881Assess:24.
Anon., 1989. Report ofthe \Vorking Group on the assessment ofthe stocks ofhake. ICES CM
1989IAssess:21.
Anon., 1990. Report ofthe Working Group on the assessment ofthe stocks ofhake. ICES CA!
19901Assess:22.
•
Anon., 1991a. Report ofthe \Vorking Group on the assessment ofthe stocks ofhake. ICES CM
1991/Assess:20.
Anon., 1991b. Report ofthe study group on the coordination ofbottom trawl surveys in sub-areas
VI, vn and Division DCa. lCES CA11991/G:13, 33 pp.
Anon., 1992. Report ofthe study group on bottom trawl surveys in Sub-areas VI,VII and VIII and
Division IXa. ICES CM 1992/G:19.
Anon.,1993a. Report of the Working Group on the assessment of Southem Shelf Demersal
Stocks. ICES CM 1993/Assess:3.
Anon., 1993b. Report ofthe Study Group on Cephalopod Biology. International Council/or the
Exploration 0/the Sea C.M. 1993/K:66.
Anon., 1994a Report ofthe study group on bottom trawl surveys in sub-areas VI, VII, and VIII
and Division IXa. ICES CA! 1994/G:6.
Anon., 1994b. Report ofthe Working Group on the assessment ofSouthem ShelfDemersal
Stocks. leES CM 1994/Assess:3.
Anon., 1994c. Report ofthe Southem Hake Task Force. Lisbon (portugal) 10-14 Getober 1994.
European Commission, Sec (94) 2231, 113pp.
Anon., 1994d. Report ofthe Working Group on Eeosystem Effects ofFishing Activities. ICES
CM 19941Assess/Env: 1, 109 pp.
-20-
•
Anon., 1994e. Report of the StiIdy Group on the Life History and Assessment of Cephalopods.
International councilfor the Exploration ofthe Sea C.M. 1994/K.:7, 32pp.
Anon., 1995a. Report ofthe Working Group on the Assessment of Mackerei, HOrSe Mackerei,
Sardine and Anchovy. ICES, CA! 1995/Assess:2, 329 pp.
Anon., 1995b. Report ofthe Working Groupon the assessment ofthe Southern ShelfDemersal
Stocks. lCES eH 1995/Assess:6.
AIton., 1995. Report of the \Vorking Group on Cephalopod Fisheries and Life History.
International Councilfor the Exploration ofthe Sea C.M. 1995/K.:3, 16pp.
.
Anon., 1996a. Report ofthe Inteinational Bottom Trawl Survey \Voridng Group. lCES CM
19961H:1.
Anon.,1996b. Report ofthe Working Group on the assessment ofthe Southern ShelfDemersal
Stocks. lCES CA! 1996/Assess:5.
Anon., 1996c. Report ofthe \Vorking Group on the Assessment of Mackerel, Horse Mackerei,
Sardine and Anchovy. lCES, CA! 1996/Assess:7, 340 pp.
Anon., 1996d. Report of the Atlanto-Scandian herring, capelin arid blue whiting Assessmerit
Working Group. lCES CA! 1996/Assess:9.
I
Anon., 1997a Report ofthe International Bottom Trawl Survey Working Group. lCES, CM
19971H:6, 50 pp.
Anon., 1997b. Report ofthe Working Group on the Assessment of Mackerei, Horse MackereI,
Sardine and Anchovy. lCES, CM 1997/ASsess:3, 384 pp.
•
Anon., 1997c. Report of the Working Group on the Assessment of southern shelf demersal
stocks. ICES, CM 1997/Assess:5.
Anon., 1997d. Report ofthe Working Group on Nephrops stockS. ICES CM 1997/Assess:9.
STCF., 1990. Report ofthe Meeting ofthe STCF Working Group on the distribution ofjuvemie
hake ofthe Southern Stock. INIP, Lisbon, 3-6 July, 1990.
VI. CRITIQUE
Iberian gfoundfish survey senes have been providing the basic information to perform the
arialytical assessments ofseveral stockS ofthe Northeast Atlantic cwrently assessed within ICES
Assessment \Vorking Groups. These surveys have been also valuable to improve the biological
parameters and to morutor the distribution of the siJecies under assessment. They have also
provided basic data for the study fish assemblages in Iberian shelf arid slope arid are the first
stone for multispecies and ecosystem studies under development in EU projects like CORMA
(FAIR) CT-95-0604.
- 21-
Species like pouting (Trisoprerus /uscus), seabreams and rock fish (He/ico/enus dacty/opterus)
not currently assessed within ICES have beeri evaluated to provide scientific advice to the
Portuguese administration using data from the groundfish surveys. The recently ICES Study
Group on the Assessment of Other Fish and Shellfish Species will consider these and other
species in Division IXa to evaluate trerids in the populations of these species and whenever
possible to evaluate their state of exploitation. The information available on the abundance and
distribution of other species not currently assessed within ICES are partly provided by the
Portuguese and Spanish groundfish survey senes.
In what concerns the sampling methodology used for the groundfish surveys this has been
directed to the goal of obtaining abundance indices disaggregated by age to tune VPA in
analytical assessments, specially for hake and horse mackerel. Atteinpts have been ~ade to take
profit of the same data senes to other species stock assessments \vith success (blue whiting,
mackerei, megriIn and four-spot-megrim). Nevertheless the PortUguese gear used (Norwegian
Campell Trawl) it is not efficient for monkfish capture and cannot rippropnately sampie these
stocks which are currently assessed within ICES. For the study ofthe distribution of monkfish
other gear than NCT hriS to be used in order to obtriin a time senes 6f abundance indices to tune
the VPA. An European Study Project (SESITS- 029/96) is under development to standardize the
groundfish gear methodology among areas and countries.
•
Possibilities of improvement
Assessment ofthe main demersal stocks exploited in the southwestern part off Europe (lCES
Sub-Areas VII, vm, and IX)
conducted by the ICES WG on the Set:them Shelf Demersal
Stocks using analytical models. \Vhen conducting these assessments VPA are tuned using
abundance indices estimated from these bottom trawl survey senes.
are
These surveys have been carried out by two decades covenng Portugal in Division IXa, Spain
in Divisions IXa and VIIlc and France in Divisions VIIIa,b and Divisions VIIg,hj. The ICES
SSDS \Vorking Group pointed out some difficulties to use these indices in the case of stocks
distributed on the whole area (hake for exarnple), due to seine discrepancies in the indices
estimated from the distinct surveys. The IBTS (International Bottom Trawl Surveys) \Vorking
Group (Anon, 1996a) straight out the lack of coordination arid standardization of these surveys,
and it has recommended the establishment of an ICES database for the Western and Southern
bottom surveys, and it pointed out the need for continuing surveys during the fourth quarter of
the year which is the most consisterit senes in this area over time. To respond to these problems
the new study project titled "Evaluation of demersal resources of Southwestern Europe from
staridardized groundfish " 029/96 ( SESITS) is in progress.
The SESITS project is under progress during 1997 and would continue during 1998. The
parteners are lEO, IPIMAR and IFREMER \vith support funding from E.U (DG XIV). The
coordination is ofthe responsability ofthe fishery biologist Dr. Francisco Sanchez (lEG).
The main objectives of SESITS project are aS follows :
1) to standardize the rnethodology ofthe bottorn trawl surveys in the area.
2) to estimate abundarice indices for the target species, analyse their spatio-temporal variability
and for some cases the possible effects ofthe hydrographie parameters (hake, for example).
3) to maintain and standarcllZe the surveys data base (Spain. France and Portugal).
4) to continue the senes ofthe surveys in Autumn.
-22 -
•
Special effort is being done in this project to the necessary standardization <>fthe methodology
of these sirrVeys. As reco~ended by the IBTS WO, estimation of the catchabilities of the
different sarnpling gears (NeT, Bakn, GOV) are planned With overlapping of the differerit
surveys (PoItUgalJSpain in the Division IXa, Spain/France in Divisions VIIIb and VIIIe). It is
expected then combination of these data should be possible. Duririg the study period some
countnes (Franee, POrt1lgal) are goirig t6 change their research vessel or their sarnpling gear.
Catchability conversion factors will be estimated. Like\Vise the creation of a data base in
standardized files is also considered.
Revision of sampling design
•
Selection of an homogeneus criteria concerning sarnpling design (depth strata, station grid, haul
monitoring, hydrographie stations scherne, ete.) is necessary. The precision of the species
abtindance indices is dependent <>fthe degree ofhomogeneity ofthe strata. It is evident that in
the ;,vhole ofthe ICES area there are different biological communities arid target species, \vhich
implies thai a desigii of strata suitable for one urea is not necessanly so for another. The target
species ofthe fleet working in the GUlf of Oidiz arid the fish commuriities present there are very
different to those found in the Celtie Sen. A first approximatiori has been made by analyzing the
data of recent years from Sparush historical series in an attempt to determine whether the
stratification used to date is suitable, Cl' if other more homogeneous strata should be adopted
\"hich provide an improvement in the preeision of indices. With mulii-species surveys, a
stratification suitable for one species is not necessarily so for others. This becomes even more
complicated wheri the same speeies~ in the different stages of its life, occupies different niehes'
Gtiveniles usUally live in more superficial \vaters thaii adults). One \"ay of dealing with the
problem is to apply multi-vanant analyses to a matrix of data to determirie the degree of
similarity between sampling stations arid to establish the mairi groupings or associations betweeri
species. Previous works ofthis type hUve been reported for the Spanish and Portuguesse waters
(Anon., 1997a, Cardador, 1997, Sanchez, 1997)
Iri general in this area the seaSonal spatial distribution of the target species as weIl
•
, ...
as their
aburidance vanability by stratum is weIl understood. The work deveIoped by the ICES Methods
Working Group has been a forUm ofuseful analysis and discussions on clarifying the appropriate
wie ofthis type ofsurveys for analytical assessmerits. They have been used in tUning methods of
the VirtUal Population Analysis,. Lauree and Shepherd (1983) Extended Stirvival Analysis
(Shepherd, 1992), Integrated Catch Analysis (Patterson and Melvin, 1996).
To irilprove the aburidance indices estimation, based cin the fixed sarnpling design iri use in the
Portuguese surveys applicatiori of generalized additive rriethods arid genernlized linear models
arid other statistical studies are expected to be further developed in the near futtife under a FAIR.
project proposed in 1997.
REFERENCES
Anon., 1996a. Repoit of the International Bottorn Tra\vl SurVey WorIdng Group. ICES CAf
19961H:1.
Arion., 1997a. Report ofthe International Bottom Trawl Survey \Vorking Group. leES, CM
19971H:6, 50 pp.
-23 -
Cochran, W.G., 1966. Sampling Techniques . John Wiley and SOllS, inc., 2nd edition
Hoskings, B.l., Draghici 1. and Davies, H.C., 1978. A new look at the Omega equation. Quart.
J. Roy. Meteor. Soc., 104:31-38.
Laurec, A. and Shepherd, J.G., 1983. On the analysis of catch and effort data J. Cons. Int. Exp.
Mer.41:81-84.
Patterson, K. R. and Melvin,.G.D., 1996. Integrated catch at age analysis Version 1.2. Scotish
Fisheries Report Number 58.
Shepherd, J. G., 1992. Extended survivors'analysis: an improvement method for the analysis of
catch-at-age data and catch-per-unit-effort data. Working paper No 11. lCES Multispecies
assessment Working Group, lune 1992, Copenhagen, Denmark, 22pp, mimeo.
STCF., 1990. Report ofthe Meeting ofthe STCF Working Group on the distribution ofjuvenile
hake of the Southem Stock. INIP, Lisbon, 3-6 July, 1990, 9 pp.
•
•
-24-
l
TABLE 1- PORTUGUESE SURVEYS: List ofsurveys, fishing days and valid hauls by survcy
LIST OF SURVEYS DURING 1979-1996
YEAR
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
TOTAL
LATE
WINTER/
SPRING
SUMMER AUTUMN
X
2 X (I)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
7
12
TOTAL FISHING DAYS BY SURVEY
YEAR
X
X
X
X
X
X
X
X
X
X
X
X
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
17
TOTAL
X
X
X
X
X
LATE
WINTER/
SPRING SUMMER AUTUMN
12
16 +9
19
14
18
18
17
17
22
17
27
23
25
23
30
22
21
21
126
(1) - SouthWest and South
1996 - RN "Capric6mio", trawl net without rollers
- 25-
245
14
19
18
33
22
TOTAL VALID HAULS BY SURVEY
YEAR
24
21
14
17
23
35
32
16
20
27
24
22
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
381
TOTAL
LATE
WINTER/
SPRING SUMMER AUTUMN
55
63 +36
67
69
69
69
70
68
101
118
88
76
114
98
119
81
66
81
468
1040
55
62
111
189
117
150
117
98
81
138
123
99
59
65
94
88
71
1717
,
Table 2 - Type ofbiological studies carried out by species using information collected from the
.Portuguese and Spanish groundfish surveys series.
Biological studies
Species
Distribution
hake, horse-mackereI, mackerel, Spanish mackerel, blue
whiting, four-spot-megrim, megrim, black and white
monkfish, lohn dory (Zeus faber), rock fish (Helico/enus
dacty/opterus), Pouting ( Trisopterus /uscus ) European
squid (Loligo vu/garis) and Veined squid (Loligoforbesi)
Length-weight relationship
hake, horse-mackerel, mackerei, Spanish mackerel, blue
whiting, European squid and Veined squid.
Age determination
hake, horse-mackerel, mackerel, Spanish mackerei, blue
whiting, four-spot-megrim, European squid and Veined
squid
Maturity
hake, horse-mackerel, mackerei, Spanish mackerei, blue
whiting, fo.rr-spot-megrim, black monkfish, European squid
and Veined squid
, Fecundity
e
horse-mackerel
Food habits
hake, horse-mackereI, mackerei, blue whiting, black
monkfish, lohn dory , European squid and Veined squid
Recruitment
hake, horse-mackereI, mackerei, blue whiting, megrim,
four-spot-megrim
Genetic
hake
Parasitism
horse mackerei, hake, mackerei
Communities, diversity
demersal fish and invertebrates
Trawl selectivity
hake, horse mackerel
- 26-
e;
Table 3 - Groundfish surveys series used in leES stock assessment Working Groups
( in VPA tuning), by species.
Survey senes
Portuguese Portuguese
Summer
Autumn
Spanish
Autumn
Source
Hake
since 1989 since 1989
since 1983
ICES, 1997a
Horse-mackerel
since 1989 since 1985
since 1985
ICES,1997b
since 1986
since 1984
ICES,1997b
Four-spot-megrim
since 1989 since 1990
since 1988
ICES, 1997a
Megrim
since 1989
(*)
since 1988
Species
Mackerel
Blue whiting
since 1985
Norway lobster
since1990
(*)
(*) used only for cpue trend analysis
- 27-
since 1985
ICES, 1997a
ICES, 1996
ICES, 1997c
,r
"
62
16°
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10°
r
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63 °
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FIGURE 1 - leES DIVISIONS Vllic and lXa - Area covered by Spanish and Portuguese Groundfish Surveys
- 28-
•
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FIGURE 2 - Spaoish surveys: depth aod geographical strata
- 29-
8·
SectCAM
SectMAT
41°00~
SectAVE
SectBER
PORTUGAL
43
Sec' L1S \
FI:XED FISHING STATIONS
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SeecSIN
SectARR
OOm
SeecSAG
SectPOR
11°00'
FIGURE 3 - Portuguese surveys: deptb and geograpbieal strata
·30·