Distribución y abundancia de Parastichopus parvimensis (Holothuroidea) en islas de la costa occidental de Baja California Sur, México, durante el periodo reproductivo

The distribution and abundance of the warty sea cucumber Parastichopus parvimensis in the islands Natividad (NI), Asunción (AI) and San Roque (SRI) on the western coast of Baja California Sur (BCS), Mexico, were examined based in independent data from commercial fishing in March and April 2009. The density was estimated from 345 sample units (SU = 10 m²) random selected between 2 and 30 m of depth. In NI, AI and SRI was found an average density and standard deviation (S) of 1.1 (1.02), 0.82 (1.06) and 0.83 (0.9) org/m2, and an average gutted weight of 158, 176, and 149 g respectively. Changes in density were analyzed using a generalized linear model (GLM) with Gamma error structure, using the variables of depth and zone (islands) as well as the interaction effect, which was significant (p < 0.01). The analysis revealed a pattern of increasing density with the depth in SRI (p < 0.01) and non-significant in NI and AI. The variability of the density was high at all depths in NI (S = 10.2) and AI (S = 10.6), while SRI was only in >10 m depth (S = 9.0), but much less in water shallow (S = 2.7). The way in which the density varies on each island seems to be modulated by physical and biological characteristics related to the substrate, since 85% of the sampling units were associated with rocky substrate. We discuss possible factors that could influence the density changes with depth.