The Effect of Temperature on Production of Gonads by the Sea Urchin Strongylocentrotus franciscanus Fed Natural and Prepared Diets

Strongylocentrotus franciscanus (248 ± 76 g wet body weight, mean and standard deviation) were maintained in the laboratory at 12.9 and 16.1 C and fed either Nereocystis luetkeana or a prepared feed for 4 mo (July through October). The size and histological condition of the gonads of an initial sample, the experimental animals, and a sample from the commercial fishery were evaluated. The gonad index of experimental S. franciscanus increased from an initial 3.4%± 1.4 to 19.2%± 3.3 (mean and standard deviation) for the four treatments. The feeding rate was greater for individuals fed N. luetkeana and for both foods at the higher temperature. Gonad production was not significantly different among the experimental treatments, indicating the prepared feed was nutritionally superior to the algal diet and an increase in catabolism at the higher temperature balanced the increase in food intake. Histological preparations determined the urchin gonads developed from an initial spent condition to the premature stage for both experimental and fishery samples, indicating neither food or temperature affected gametogenesis.