Reproductive cycle of the red sea cucumber,Parastichopus tremulus(Gunnerus, 1767), from western Norway

The red sea cucumberParastichopus tremulusis considered a potentially valuable fishing resource and a candidate for aquaculture in Norway. The aim of this study was to advance the information about the reproductive cycle ofP. tremulusin Norway. Specimens were obtained monthly from by-catch in a coastal commercial crustacean fishery from the fjord system around angstrom lesund, More and Romsdal county (62 degrees N-6 degrees E, 100-200 m depth). Of the 258 individuals that were examined, 218 possessed gonads, with an estimated female:male ratio of 1.3:1. A seasonal pattern of gonadal growth was documented, and the spawning period indicated. The gonad index (GI) increased from January, peaked in May (GI similar to 7%) and then decreased until September. Spawning animals were observed in June and July. In the period August to October the gonads were empty (spent). From November to February most gonads appeared to be in a resting stage. Sea cucumbers held in captivity showed a similar pattern, but had a significantly lower GI compared with wild caught animals in May and June. The results from our study add to the limited biological knowledge onP. tremulusfrom Norwegian waters and provide important information both for a future management of commercial fishery and for the development of red sea cucumber in aquaculture.