ESTIMATES OF REPRODUCTIVE POTENTIAL AND TIMING IN CALIFORNIA SEA CUCUMBERS PARASTICHOPUS CALIFORNICUS (STIMPSON, 1857) FROM SOUTHEAST ALASKA BASED ON NATURAL SPAWNING

摘要

Accurate estimates of fecundity and spawn timing are essential to fisheries management but can be difficult to obtain in nonaggregating broadcast-spawning species such as the commercially harvested sea cucumber Parastichopus californicus. Individuals of P. californicus collected from Southeast Alaska (SEAK) over 3 y were examined to determine the timing of spawning based on seasonal variations in gonad indices (GI). Gonad indices measured at different time points in the annual reproductive cycle were compared with gonad lipid content and egg development to validate GI as an indicator of gonad maturation. Fecundity was estimated as the total number of eggs and as the number of viable eggs produced in both live-spawned and strip-spawned animals. Results suggest spawning may occur slightly earlier than previously reported in British Columbia, Canada, where fecundity was about two times higher than in SEAK. Seasonal changes in gonad total lipid and maturation stage were recorded. Gonad index was moderately correlated with both gonad lipid content and maturation stage. Estimates of total fecundity and viable eggs based on live spawning did not significantly differ among the 3 y sampled. Live spawning yielded comparable estimates of total fecundity and viable eggs per gram female wet weight compared with strip spawning. These findings inform aquaculture efforts and management of the commercially harvested SEAK population of P. californicus.