Transport stress catabatic effect of anesthetic benzocaine on American shad Alosa sapidissima

American shad,Alosa sapidissima,is an anadromous fish.Its fertilized eggs were introduced from U.S.A.into China from 2000 and a certain large scale of larvae and fingerlings were first obtained in 2003.While the fish were highly stressful to flash light,noise,handling and transportation.Long-distance transportation of American shad fingerlings could hardly realized for the subsequent high mortality of the fish,which had became the bottlenecks in scale-cultivation and industrialization of American shad.It is necessary to know how the transport stress affect on the fish and accordingly,anesthetics were thought to deal with the problem.So the changes of hormonal(cortisol) and blood biochemical parameters in 1~(+) year old American shad were investigated with unstressed fish before transportation(Control-fish),fish after 2 h transportation without anesthetics(Ⅰ-fish) and fish after 2 h transportation with 20 mg/L anesthetic benzocaine(Ⅱ-fish).The results showed that the serum cortisol and blood biochemical parameters were obviously changed after transport stress.The serum cortisol in Ⅰ-fish[(41.97±17.92)?ng/mL,n=9] and Ⅱ-fish[(15.62±1.80)?ng/mL,n=9] were obviously 20 times and 4 times respectively higher than in Control-fish[(2.05±1.48)?ng/mL,n=10] and serum cortisol in Ⅰ-fish was also obviously higher than Ⅱ-fish(P0.05).The concentrations of serum TP,AP,AKP,CHE,ALT,K~(+),Ca~(2+) and GLU in Ⅰ-fish were obviously higher,and values of AP/GP was obviously lower than that in Control-fish(P0.05),while no significant difference of the blood biochemical parameters mentioned above were observed between Ⅱ-fish and Control-fish.The concentrations of serum LDH and AST in Ⅰ-fish and Ⅱ-fish were no obviously higher than those in Control-fish(P0.05).The concentrations of serum TC and TG in Ⅰ-fish showed no significant difference with Control-fish but were obviously different with Ⅱ-fish(P0.05).All the results indicated that the tissues of American shad such as heart and liver had been harmed,which may cause the failure in long-distance transportation of American shad.The results also showed that the anesthetic benzocaine was benefit for maintaining the stability of the biochemical parameters in fish and had the obviously catabatic effect to the transport stress.