大口黑鲈F4代耐盐选育品系盐度耐受和生长性能评估OA

As a major economic fish,the Micropterus salmoides has significant aquaculture potential in saline-al-kaline waters.This study focused on the F4 generation salt-tolerant selection population(F4),the'Youlu No.3'population(A),and the Jiangmen cultured population(B)to evaluate the breeding effects of salt-tolerant M.salmoides lines.Their mortality under acute salinity stress and changes in growth,osmoregulation,antioxidant capacity,and digestive enzymes under long-term 9 salinity stress were assessed.The results showed that the 96-hour LC50 of the F4 population was 14.37,significantly higher than those of the A(13.79)and the B(13.03)polulations,indicating that the F4 population has a higher tolerance threshold.Long-term trial results demonstrated that the F4 population exhibited advantages in body weight gain,daily weight gain,and specific growth rate,particularly during days 0-60.Although there were no significant differences in serum osmolali-ty,Na+/K+-ATPase(NKA),and Ca2+-Mg2+-ATPase(CMA)activity among the three populations,the F4 population had significantly higher serum cortisol(Cor)concentrations and expression levels of ATP1a3a and NKCC1a compared to populations A and B,indicating stronger osmoregulatory capacity.Antioxidant results showed that the F4 population had significantly higher enzyme activities of superoxide dismutase(SOD),cata-lase(CAT),and acid phosphatase(ACP)than populations A and B,while malondialdehyde(MDA)concentra-tions were significantly lower.Furthermore,pancreatic lipase(PL)and trypsin activities in the F4 population were also significantly higher than those in populations A and B.In summary,the F4 generation of salt-tolerant M.salmoides demonstrated better adaptability and growth performance under salinity stress.The results of this study provide valuable information for breeding freshwater fish with salt tolerance and serve as a reference for expanding and applying of M.salmoides aquaculture in brackish and freshwater environments.