Changes in plasma vitellogenin, phosphorus and calcium in wild-caught female carp (Cyprinus carpio) as potential criteria for selecting brood-fish for restocking natural populations

Abstract

Despite two decades of artificial spawning of wild carp (Cyprinus carpio) to rehabilitate natural populations in the southeastern Caspian Sea, there are still no appropriate physiological criteria for selecting competent brooders during induced spawning. To this end, the plasma concentrations of vitellogenin (Vtg), phosphorus (P) and calcium (Ca) were measured during ovarian development, as potential criteria for selecting ripe brooders. Vtg was measured by ELISA using pure carp Vtg and its specific antibody. P and Ca contents of plasma samples were also determined photometrically and colorimetrically, respectively, by Autoanalyzer using commercial specific kits. The plasma levels of Vtg showed no significant differences during sampling times, whereas its highest significant value (922±301 μg/ml) was recorded in late vitellogenesis (P≤0.05). The plasma concentrations of Ca also showed no significant differences in different stages of ovarian development except for late vitellogenesis (16.65±1.77mg/dl) and during sampling times except for June (17.24±1.76mg/dl) that rose to its peak. The plasma levels of P increased gradually during sampling times and reached maximum value in June (35.22±11.12mg/dl). Level of P also increased gradually during ovarian growth and peaked at late vitellogenesis (33.94±8.02mg/dl) and slowly decreased afterward. The regression analysis indicated that plasma P levels showed a high correlation with plasma Vtg concentrations. Therefore due to easier and lower cost of plasma P measurement in fish in comparison with Vtg, measurement of plasma P levels is recommended as criterion for selecting ripe females for artificial spawning.