Size at First Maturity of elected Sea Cucumber

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SIZE AT FIRST MATURITY OF SELECTED SEA CUCUMBER
SPECIES IN LA UNION
Jinnie Mamhot
E – International Scientific Research Journal, VOLUME – V, ISSUE – 1, 2013, ISSN 2094 - 1749
Table of Contents
Abstract
2
Introduction
2
Results and Discussion
4
References
7
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SIZE AT FIRST MATURITY OF SELECTED SEA CUCUMBER
SPECIES IN LA UNION
Jinnie R. Mamhot
ABSTRACT
To properly manage a resource, some biological information should be
considered. Aside from where and when a species occurred, aspects of reproduction
prove to be valuable information needed to establish management option for a species.
Being an important marine commodity and because of declining landings of sea
cucumber, a study was conducted to generate information on reproduction of species.
This paper attempted to provide data on maturity of sea cucumber.
Keywords: Sea cucumber, La Union, size at first maturity, Holothuria atra
INTRODUCTION
Holothurians, known as sea cucumbers, are marine organisms which
inhabit shallow-water sediments found in almost all marine environments in the
world. They thrive in all tropical and temperate oceans, mostly in tropical IndoPacific region (Conand, 2004). Large demand of this commodity for food and
medicine purposes led to overexploitation of sea cucumber worldwide. A
sustainable exploitation of this resource requires the estimation of sex maturity
which will limit capture sizes which has a biological justification in maximizing the
yield per recruit, allowing individuals to spawn before harvest (Navarro et. al,
2012).
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Results and Discussion
Few individuals showed full maturity (ripe gonads). In this report, the
percentage of mature gonads also included those of developing and maturing
stages in which sea cucumbers may reproduce. The size classes at which 0
percent and 100 percent of the individuals were determined on the curve and the
point at which 50 percent of the size class are sexually mature may be used as
an index of the size at first maturity. The criteria used in this work include forms
of the gonadal tubules, color, and consistency and degree of fullness of the
gonads (Conand, 1975) (Fig. 1) as described by Al-Rashdi et al. (2007).
A. Female H. atra, developing/
maturing stage
B. Male H. atra, developing/
maturing stage
C. Testis of mature
male (H. atra)
D. Ovary ofmature
female (H.atra)
Fig. 1. Gonads of male and female H. atra (A-D)
A small incision on the anterior dorsal of the animal was made and the
animal was gently squeezed to let the gonads come out, ready for examination.
Sexes of most holothurids are separate but not discernible in young individuals.
Morphological features particularly the external characteristics are of no help in
distinguishing male from female individuals. However, gonadal examination by
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dissection of adults will show the sexes of the sea cucumber: cream color of
male testis and orange coloration of ovary for mature female.
In the analyses, figures were separate for male and female. In some
cases only one sex was reported due to few numbers of individuals with mature
gonads (A.echinites, H. deficilis and H. hilla). In others, pooled data from two
sites were used (H. leucospilota). In table 1, the holothurid, A. echinites, though
quite abundant in Balaoan samples were mostly immature. However, pooled data
from Balaoan and San Fernando showed length at first maturity at 8. 9 cm. The
majority of the H. deficilis, a very abundant species and occurred only in San
Fernando, was mostly immature. Mature individuals were common at size 3.8
cm. Members of the family were also known to reproduce by fission. H. hilla was
also an abundant species in San Fernando and most of the individuals with
ripening gonads were males with length at first maturity at about 7.6 cm.
Table 1. Length at first maturity of sea cucumber from La Union
Species
A.echinites
H. deficilis
H. hilla
H. atra
H. fuscocineria
H. scabra
H. albiventer
H. ocellata
H leucospilota
Female
14.8
23.5
16.9
13.8
19.1
21.8
- Few samples
N
(15)
(54)
(13)
(7)
(8)
(32)
Male
9.3
3.8
7.6
14.8
23.6
17.7
11.8
18.9
25.2
N
(13)
(19)
(32)
(81)
(24)
(27)
(17)
(17)
(22)
Sampling area
Balaoan
San Fernando
San Fernando
San Fernando
Balaoan
Sto. Tomas
Sto. Tomas
Sto. Tomas
San Fernando
and Balaoan
N- number of samples
H. atra, the most studied species among the holothurids differs in length at
first maturity. Abdel-Razek (1994) reported length at first maturity for this species
at 16.5 for males and 15.5 for females with calculated values at 17.5 for females
and 16.5 cms for males. Compared to the findings in this work, the length at first
maturity was somewhat smaller, about 14.8 centimeters for both sexes.
Pooled data for H. fuscocineria shows length at first maturity for both
males and females to be similar (about 25.6 cm). Male H. scabra was found to be
sexually mature at 17.7 cm while females mature earlier at 16.9 cm. Kithakeni
et al. (2002) reported the length at first maturity of H. scabra along the coast of
Dar es Salaam to be at 16.8 cm which agrees with the findings in this study.
However, it was not known whether the size is for male or female individual.
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Males of H. albiventer were already mature at 11.8 cm while females mature later
at 13.8 cm (Table 1). Both male and female male were sexually matured at about
19.0 cm. The combined data using Balaoan and San Fernando samples show
sexual maturity for H. leucospilota at length 25.0-26.0 cm for male while female
mature earlier at 21.0-22.0 cm.
The findings here may not be conclusive for reasons that for some species
only few individuals had clear and discernible maturity stages. The categories
used were based on the species H. atra and on the morphological
structures/features of the gonads only. No histological analysis was made and
thus no added information on eggs and sperm development was gathered.
These are important considerations to conclude spawning categories of sea
cucumbers. Moreover, there was no data on gonadal index and thus no
periodicity on the gonadal maturation could be established. Nevertheless, the
estimated length at first maturity described in here may offer a comparison for
data needed on reproductive sizes of concerned taxa. Dissected samples
showed no define patterns or seasonality of gonad maturation.
In most species studied, mature and developing/mature gonads were
recorded in most months (H. atra, H. fuscocineria and H. leucospilota). Some
however, were observed in only some months (H. ocellata, H. albiventer and H.
deficilis). Protracted occurrences of mature gonads may indicate longer duration
or year round reproduction of a species. Peak spawning is indicated by high
number of mature individuals. A shorter occurrence may indicate distinct
spawning period.
A. echinites showed low number of individual with developing gonad, and
seemed to have two spawning cycles. H. leucospilota in both northern sites
showed mature gonads in almost all months. Developing stages seemed to be
from July to December for H. deficilis. H. albiventer had developing gonads from
June to August with some mature gonads in July. H. scabra had developing
gonads the year round but mature gonads were evident from April to May and
December to January. H. ocellata had developing gonads from September to
November. No mature gonads were observed. H. atra had developing/ maturing
and mature gonads in almost all months while H. hilla had developing gonads in
May and in August to October and with mature gonads in October. H.
fuscocineria had year round developing/ maturing stages. Mature gonads were
also scattered throughout the year.
These findings hope to contribute information that will justify management
measures for the sea cucumbers of La Union.
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References:
Al-Rashdi K. M., S.S. Al-Busaidi and I.H. Al-Rassadi. 2007. Status of the sea
cucumber fishery in the Sultunate of Oman. SPC Beche de mer Information
Bulletin 25: 17-21
Conand, C. 2004. Present status of world sea cucumber resources and
utilization: An international overview. In: Advances in Sea Cucumber
Aquaculture and Management, A. Lovatelli, C. Conand, S. Purcell, S.
Uthicke, J.F. Hamel and A. Mercier (Editors), pp 13-23. Geneva: FAO
Fisheries Technical Paper.
Conand, C. 1975. Maturite sexuelle et fecondité du Tassergal, Pomatomus
saltator (L., 1776), Poissons-Pomatomidae. Bull. Inst. Fond. Afr. Noire (A).
37: 395–466
Navarro, P. G., Sanz, S.G., & Tuya, F.2012. Reproductive biology of the sea
cucumber Holothuria sanctori (Echinodermata: Holothuroidea)
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Size at First Maturity of elected Sea Cucumber

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