The Physiological Adaptation Of Stocking Silver Carp And Bighead Carp To Water Environmental Change In The Three Gorges Reservoir Water Ranch

In this study, we chose stocking economic fishes, silver carp and bighead carp, as experimental fishes. The farmed pond-rearing silver carp and bighead carp were stocked into in situ cage in Three Gorges Reservoir water ranch. Physiological and biochemical methods were used to analysis the changes of indices of blood and hepato-pancreas in silver carp and bighead carp.The results show that, the indices in silver carp liver, such as acid phosphatase (ACP), superoxide dismutase(SOD), catalase(CAT) and some indices in serum, such as alkaline phosphatase(ALP), alanine aminotransferase(ALT), aspartate aminotransferase (AST), lactate dehydrogenase(LDH), choline esterase(CHE), total protein(TP), triglyceride(TG), total cholesterol(TC), creatinine(CREA), total bilirubin(TBIL):119.82±3.68U/gprot,7.69±0.25U/mgprot,44.01±12.63U/mgprot,9.05±0.69U/L,32.08±3.32U/L,85.66±9.44U/L,405.92±40.96U/L,1440.40±79.36U/L,22.50±0.54g/L,1.05±0.06mmol/L,2.86±0.12mmol/L,1.48±0.16μmol/L,0.65±0.06μmol/L, have a downward trend after the first rise and the indices keep stable at last. The ALP, ALT, AST, LDH, CHE, TP, TG and TBIL reach the top after5days of stocking; After10days of stocking, the TC and CREA reach the top; After68days of stocking, the ACP, SOD, CAT in liver and the ALP, ALT, AST, LDH, CHE, TP, CREA, TBIL in serum all recover to the level before releasing (P>0.05); While comparing with the level before releasing, TG in the serum significantly decreases (P<0.05) and TC in the serum significantly increases (P<0.05).Before stocking, the indices in bighead carp are ACP(125.64±3.46U/gprot), SOD (10.34±0.16U/mgprot), CAT(26.21±1.41U/mgprot). ALP(93.05±18.26U/L), ALT (60.40±4.86U/L), AST(99.29±5.51U/L), LDH(1403.82±108.99U/L), CHE (351.28±14.37U/L), TP(24.04±0.36g/L), TG(0.79±0.05mmol/L), TC(4.10±0.11mmol/L), CREA(3.52±0.17μmol/L), TBIL(3.54±0.07μmol/L), After stocking, the indices in liver, such as ACP, ALP first increase and then decrease; SOD, CAT in liver and ALT, AST, LDH, TG, CREA, TBIL in serum first decrease and then increase; CHE, TP, TC in serum have a decreased trend; After5days of stocking, ACP and ALP reach the top; After10days of stocking, SOD and CAT in liver fall to the lowest; After14days of stocking, TG and TBIL in serum fall to the lowest; After28days of stocking, ALT, AST and LDH fall to the lowest; After68days of stocking, ACP, SOD in liver and ALT, AST, TG, CREA in serum all recover to the level before releasing (P>0.05); While comparing with the level before releasing, CAT in the liver significantly increases (P<0.05) and LDH, CHE, TP, TC, TBIL in the serum significantly decrease (P<0.05).The results indicate that shortly after stocking, the silver carp’s antioxidant capacity enhances and liver and kidney damage and phosphate group transfers and metabolism of lipid enhances. The14days after releasing, most functions of silver carp gradually recover and reach the level before releasing on the68days. Shortly after stocking, the bighead carp’s antioxidant capacity declines and liver and kidney metabolism restrain and phosphate group transfers and metabolism of lipid enhances.28days after releasing, most functions of bighead carp gradually recover and some functions are still recovering to the level before releasing on the68days.The results show that the silver carp and bighead carp exhibit some differences in the process of adapting to the environment. It may be caused by the change of temperature and the differences of dietary. Silver carp mainly feeds on phytoplankton while bighead carp mainly feeds on zooplankton. Because water temperature gradually decreases, silver carp and bighead carp undergo environmental stress state. While the water temperature drops, the zooplankton likely distributes deeper water in experiment season, so the food of bighead carp will reduce or diminish and thus silver carp and bighead carp perform differences in adaptation to the environment change. Therefore, in order to enhance the adapting ability of stocking silver carp and bighead carp in the Three Gorges reservoir, the present results suggest that it is necessary that silver carp and bighead need a appropriate environmental adaptive training before releasing.The above results suggest that the transferring silver carp and bighead from farm pond to nature water can cause environmental stress. It needs a physiological adaptation period of one to two months to regulate their physiological function to homeostasis. The findings will facilitate to understand the physiological adaptation process when silver carp and bighead carp are transferred from farm pond to natural water environment. The results will be as instructions for silver carp and bighead carp propagation and releasing to the natural water and stocking in water ranch, and also can provide some new data for physiological studies of fish to adapt to environment change.