THE EFFECT OF TEMPERATURE ON FATIGUE INDUCED CHANGES IN THE PHYSIOLOGY AND SWIMMING ABILITY OF JUVENILE ARISTICHTHYS NOBILIS (BIGHEAD CARP)

Aristichthys nobilis (bighead carp) is a commercially valuable fish with a natural range extending from southern China to the Amur River. Dams interfere with spawning migrations and reproduction in wild populations has declined and effective fish passages are needed. To obtain data for the design of effective fish passages for A. nobilis, a laboratory study of the swimming ability of juvenile A. nobilis was conducted in a flume-type respirometer. Critical swimming speed (Ucrit) was determined at five temperatures (5, 10, 15, 20 and 25℃) and Ucrit increased significantly (P0.05) with increasing temperature, reaching a maximum of 7.01 BL/s (1.19 m/s) at 25℃. The physiological stress caused by swimming to fatigue was assessed by measuring serum levels of total protein (TP), blood glucose (Glu) and triglyceride (TG) before and after fatigue at 5, 10, 15, 20 and 25℃. At fatigue, serum levels of TP, Glu and TG were significantly higher (P0.05) than before fatigue. Furthermore, when the water temperature was below 15℃, serum levels of TP, Glu and TG tested at fatigue were significantly higher than those tested at fatigue in water above 15℃. This investigation provides data on the physiological response of A. nobilis to exercise fatigue and the effect of environmental stress produced by suboptimal temperature. Results will contribute to the fields of fish physiology and conservation management and provide information valuable for designing effective fish passages.