Zhiying Tu

Swimming capability and swimming behavior of juvenile acipenser schrenckii.

Acipenser schrenckii, the Amur Sturgeon, was a commercially valuable fish species inhabiting the Amur (Heilongjiang) River but populations have rapidly declined in recent years. Dams impede A. schrenckii spawning migration and wild populations were critically endangered. Building fishways helped maintain fish populations but data on swimming performance and behavior was crucial for fishway design. To obtain such data on A. schrenckii, a laboratory study of juvenile A. schrenckii (n = 18, body mass = 32.7 ± 1.2 g, body length = 18.8 ± 0.3 cm) was conducted using a stepped velocity test carried out in a fish respirometer equipped with a high-speed video camera at 20°C. Results indicate: (1) The counter-current swimming capability of A. schrenckii was low with critical swimming speed of 1.96 ± 0.10 BL/sec. (2) When a linear function was fitted to the data, oxygen consumption, as a function of swimming speed, was determined to be MO2  = 337.29 + 128.10U (R(2)  = 0.971, P < 0.001) and the power value (1.0) of U indicated high swimming efficiency. (3) Excess post-exercise oxygen cost was 48.44 mgO2 /kg and indicated excellent fatigue recovery. (4) Cost of transport decreased slowly with increased swimming speed. (5) Increased swimming speed led to increases in the tail beat frequency and stride length. This investigation contributed to the basic science of fish swimming behavior and provided data required for the design of fishways. Innovative methods have allowed cultivation of the species in the Yangtze River and, if effective fishways could be incorporated into the design of future hydropower projects on the Amur River, it would contribute to conservation of wild populations of A. schrenckii. The information provided here contributes to the international effort to save this critically endangered species. J. Exp. Zool. 319A:149-155, 2013.

Aerobic Swimming Performance of Juvenile Largemouth Bronze Gudgeon (Coreius guichenoti) in the Yangtze River

Largemouth bronze gudgeon (Coreius guichenoti), a fish species once abundant in the Yangtze River, has been rapidly declining in recent years. One important factor, among many, is the interruption of the free-flowing rivers by dams. To obtain data that can be applied to the design of an effective fishway for C. guichenoti and other species in the fish community, a laboratory study of juvenile C. guichenotis swimming ability and energetics was conducted in a flume-type respirometer equipped with a high-speed video camera system to record swimming behavior. The critical swimming speed (Ucrit ), standard metabolic rate (SMR), and maximum metabolic rate (MO2,max ) were determined during steady swimming at four water temperatures (10, 15, 20, and 25°C). A power function accurately describes the relationship between oxygen consumption rate (MO2 ) and swimming speed (U) at the four temperatures. The Ucrit , SMR, MO2,max , and metabolic scope increased with increasing temperature. The relationship between cost of transport (COT) and U was characteristically inverse bell-shaped, with minimum COT at Uopt = 4.5-5.0 body lengths per second (bl sec(-1)). This investigation provides data on the swimming ability of C. guichenoti that will add to the basic science required for fishway design.

Integrating water flow, locomotor performance and respiration of Chinese sturgeon during multiple fatigue-recovery cycles.

The objective of this study is to provide information on metabolic changes occurring in Chinese sturgeon (an ecologically important endangered fish) subjected to repeated cycles of fatigue and recovery and the effect on swimming capability. Fatigue-recovery cycles likely occur when fish are moving through the fishways of large dams and the results of this investigation are important for fishway design and conservation of wild Chinese sturgeon populations. A series of four stepped velocity tests were carried out successively in a Steffensen-type swimming respirometer and the effects of repeated fatigue-recovery on swimming capability and metabolism were measured. Significant results include: (1) critical swimming speed decreased from 4.34 bl/s to 2.98 bl/s; (2) active oxygen consumption (i.e. the difference between total oxygen consumption and routine oxygen consumption) decreased from 1175 mgO2/kg to 341 mgO2/kg and was the primary reason for the decrease in U crit; (3) excess post-exercise oxygen consumption decreased from 36 mgO2/kg to 22 mgO2/kg; (4) with repeated step tests, white muscle (anaerobic metabolism) began contributing to propulsion at lower swimming speeds. Therefore, Chinese sturgeon conserve energy by swimming efficiently and have high fatigue recovery capability. These results contribute to our understanding of the physiology of the Chinese sturgeon and support the conservation efforts of wild populations of this important species.

Effect of vertical slit turbulence on metabolism and swimming behavior of juvenile grass carp (ctenopharyngodon idella)

Baffles were incorporated into the swim chamber of a flume-type swimming respirometer, and the effect of vertical slit turbulence on the swimming behavior and metabolism of juvenile grass carp were investigated. Results showed a significant lower TBF in turbulent flow than in laminar flow (p< 0.05). However, differences in TBF at different inlet velocities were not significant (p> 0.05), whether the fish passed through the baffles or not. In turbulent flow, the residence time ratios of test fish at different flow zone were low water velocity > medium velocity > high velocity. Oxygen consumption rate (MO2) increased with flow velocity and was higher in turbulent flow than in laminar flow. Further, the speed exponent c, in turbulent flow, was significantly higher than in laminar flow, indicated a decrease swimming efficiency. This study of fish swimming in turbulent flow extends knowledge of fish ecology and provides data for guiding the design of hydrokinetic turbulent where needed, so preventing ecological impacts.

Physiological responses to swimming fatigue in juvenile largemouth bronze gudgeon Coreius guichenoti : SWIMMING RESPONSES IN C. GUICHENOTI

Stepped velocity tests were conducted on juvenile largemouth bronze gudgeon Coreius guichenoti in a swim tunnel respirometer, and oxygen consumption increased with swimming speed to fatigue and then decreased during recovery. Serum levels of total protein, glucose and triglycerides initially decreased, increased at fatigue and then decreased during recovery. Levels stabilized after 120 min, corresponding to the time necessary to recover from fatigue.