The breeding pattern and variations in timing and reproductive output of the commercial sea cucumber Holothuria fuscogilva in Kenya

Abstract

Abstract-The sea cucumber Holothuria fuscogilva is currently one of the most commercially valuable species of sea cucumber worldwide. This study investigated reproduction of this species in order to characterize the reproductive pattern and evaluate the relationship with temperature, light and lunar periodicity. Individuals were collected monthly, between 1998 and 2007, at Shimoni, Kenya and processed using standard gonad index methods and macroscopic and microscopic observations of the gonads. Gametogenesis commenced from May and spawning occurred from December to April of each year and there was close synchrony between the sexes, contrary to the hypothesis that breeding patterns on the equator will be continuous and less synchronized between sexes. Peak spawning occurred during the last quarter of the moon. The gonad index of individuals correlated significantly with gonad tubule length and fecundity indicating that it was a good predictor of sexual maturity and reproductive output. The gonad index showed a significant correlation with temperature but not light, suggesting that temperature may play a role in controlling reproduction. The life history strategy of this sea cucumber included a higher energetic investment in the reproductive output of females and spawning at a time favorable for larval development. There was a shift in sex ratio from unity to significantly more males over the sampling period, as well as a significant reduction in mean sizes (body wall weight) and reproductive output (gonad index) suggesting that the reproductive success of this species was potentially negatively affected by fishing.

Reproductive biology of Holothuria fuscocinerea (Echinodermata: Holothuroidea) from Oaxaca, Mexico

“…Although several studies, especially in the genus Holothuria, have been carried out on sea cucumber reproduction and its relationship to environmental factors, both near the Equator (e.g. Pearse 1968, Conand 1993, Reichenbach 1999, Ramofafia et al 2001, Abdel-Razek et al 2005, Muthiga 2006, Gaudron et al 2008, Muthiga & Kawaka 2009 and at higher and lower latitudes (e.g. Gutt et al 1992, Hudson et al 2003, Despalatovi et al 2004, Galley et al 2008, Baillon et al 2011, Martinez et al 2011), a fundamental barrier to improvements in the management of sea cucumber fisheries is a lack of data regarding the basic biological parameters of the most exploited species (Conand & Sloan 1989, Conand 2001.…”

Notes on the Reproductive Traits of Holothuria fuscogilva Cherbonnier, 1980 from Laguindingan, Misamis Oriental, Philippines

“…Sex ratio of male to female white teatfish did not show significant variation which may imply that the H. fuscogilva population in the area is not subject to fishing pressure (Muthiga and Kawaka, 2009). This is not surprising because of the absence of active collection or trading of H. fuscogilva in the area.…”

“…Ten tubules were selected from each preserved gonad sample for macroscopic and microscopic examination, noting their morphological characteristics such as color, tubule length, diameter, frequency of bifurcation, and branching. Gonad tubule length was measured from the gonad basis to the tip of the tubule (Muthiga and Kawaka, 2009 using a tape measure. Gonad basis is a structure where individual gonad tubules are collectively connected which is then connected to the gonoduct (Ramofafia et al, 2000;Hamel and Mercier, 2007).…”

“…The observed morphology of the male and female gonads of H. fuscogilva in the study is similar to those observed by Ramofafia et al (2000) in the Solomon Islands while the presence of different tubule length groups is akin to those observed in Holothuria whitmaei (Shiell and Uthicke, 2006) in the Indian and Pacific regions of Australia. Variation in lengths, diameters, and frequency of bifurcations between maturity stages as shown in Table 1 can be attributed to the fact that gonad tubules increase in size and in the number of tubule branches to increase the volume of the gonads as gametes developed (Ramofafia et al, 2000;Muthiga and Kawaka, 2009). The marked variation in tubule length can be an indication that H. fuscogilva follows the Tubule Recruitment Model (TRM) wherein tubules are progressively recruited from the base of the anterior gonad that eventually develops to become the fecund tubules (Sewell et al, 1997), although Ramofafia and Byrne (2001) suggested that H. fuscogilva from the Solomon Islands did not conform to TRM considering the absence of distinct tubule cohorts and progressive tubule recruitment in white teatfish and the synchronous gamete development across tubule length groups.…”

“…Much of our knowledge regarding the reproductive biology of the white teatfish is derived from limited pioneering studies, such as those of Conand (1981); Reichenbach (1999); Ramofafia et al (2000); and Muthiga and Kawaka (2009), which provided various detailed descriptions of the reproductive behavior and timing of this commercially important holothurian species. In the Philippines, a CHED-funded project by De Guzman and Quiñones in 2011-2012 reported viable populations of H. fuscogilva in Capayas Island Marine Sanctuary of Lopez Jaena, Misamis Occidental.…”