Effect of Reproductive Status on Some Biochemical Parameters in American Shad

The pattern of some blood biochemical parameters of adult American Shad Alosa sapidissima was investigated during their reproductive cycle. A total of 288 subadult broodfish were captured between October 2015 and September 2016, of which 10 broodfish for each developmental stage were selected based on similar length and weight to evaluate the overall health status of the fish. The results showed that the serum levels of total protein, albumin, globulin, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, low-density lipoprotein, high-density lipoprotein, plasma glucose, triglycerides (TG), total cholesterol (TC), Ca2+, and P of the American Shad broodstock (females and males) significantly increased as their gonads developed, reaching the highest levels at stages IV and V, after which the above-mentioned parameters substantially decreased at stage VI. The TC and TG levels in females significantly increased from stage II to stage V and then the levels began to decrease after spawning (stage VI), but there was no significant difference in TC and TG levels in males. With the development of the gonads, the plasma glucose, superoxide dismutase, catalase, and lysozyme levels in both male and female broodfish showed different degrees of decline; in stages V (spawning period) and VI (postnatal period), these parameters significantly decreased. The results of this study indicate that physiological parameters (e.g., blood glucose level, blood lipid level, and antioxidant capacity) of American Shad broodfish, especially females, show varying degrees of reduction during reproduction, which suggests that nutritional imbalance significantly reduces immunity during the postnatal period.