Effects of three feeding models on growth,gonad yield and gonad quality of the sea urchin(Strongylocentrotus intermedius)

Effects of three feeding models on growth rates throughout the whole growth cycle,gonad yield and gonad quality at harvest of the sea urchin Strongylocentrotus intermedius were studied.Six-month-old sea urchins were selected and fed on three diets kelp(E1),kelp+mussel(E2),maize+mussel(E3)to harvest.The test diameter and live body weight of sea urchins were measured every two months.The gonad weight,gonad moisture content and gonad color were measured at the end of the experiment.Results showed that:the feeding model significantly affected(P0.01)the test diameter and live body weight of the sea urchin during its growth stage.The test diameter and live body weight performed as:E2E1E3 among feeding models.The feeding model significantly affected most specific growth rates(SGRs)of the test diameter and live body weight(P0.01),which ranked as:E2≥E1E3.The feeding model significantly affected the gonad yield and gonad quality at harvest(P0.05 or P0.01).E2[female:(7.58±1.21)g,male:(7.74±1.95)g]was the optimal model for the gonad wet weight,followed by E1 [female:(4.50±1.20)g,male:(4.87±1.02)g].E3[female:(2.66±1.02)g,male:(2.32±0.75)g]was the worst model.E2(female:15.07%±1.84%,male:15.83%±3.01%)was the optimal model for the gonad index,followed by E1(female:11.54%±4.94%,male:11.84%±3.70%)and E2(female:12.48%±4.33%,male:12.78%±3.73%).E2 and E1 were the optimal models for the gonad moisture content and gonad color,while E3 was the weakest.Effects of the feeding model on male or female sea urchins were similar.The result suggested that,S.intermedius can grow good test diameter by feeding kelp only.Animal protein can significantly improve the growth rate and gonadal production of S.intermedius.Kelp+mussel model can be applied to improve the culture efficiency of the sea urchin.Maize had no beneficial effect on the promotion of the growth,gonad yield and quality of the sea urchin.Even if animal protein was added,maize+mussel can hardly be an alternative feeding model in aquaculture of S.intermedius.