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The migration time of newly hatched Acipenser sinensis from the spawning area (river km 1675) to the Yangtze estuary (rkm 0) was ascertained in the years 1996–2007 (time range 192–243 days), and its relationship to water levels surveyed at 12 typical hydrological monitoring stations in the middle and lower reaches of Yangtze River was determined. Migration time showed a positive correlation (R = 0.621−0.738, P = 0.013−0.041) with the water levels surveyed during April at eight stations (from Jianli to Anqing, rkm 1356.2 to rkm 639.4). Stepwise regression analysis indicated that when the water level at a typical station, Luoshan (rkm 1244.2), increased by 1 m, migration time deferred 11.6 days. The high water level created expanded riparian habitat and thus may have prolonged juvenile residence time. This variable residence time due to variations in water flow caused by the Three Gorges Project needs to be addressed, and more investigation is required.

Chinese sturgeon ( Acipenser sinensis Gray, 1835) eggs from wild females ('wild eggs') and eggs from females reconditioned in freshwater ('freshwater eggs') were compared for biochemical factors related to their good chemical and physical condition and successful fertilization. Dry weights did not differ between the two groups of eggs. Wild eggs had a significantly higher protein content but lower lipid content than freshwater eggs. There were multiple and significant differences in the fatty acids between eggs from the two groups, but there was no difference for vitellin (Vn). The levels of phosphorus (P), magnesium (Mg), vitamin A ( VA) and vitamin E ( VE) in wild eggs were significantly higher than in freshwater eggs, but calcium (Ca) and zinc (Zn) levels did not differ between the two groups. These results can be used to discriminate wild eggs and reconditioned eggs. Also suggested is to decrease lipids and increase protein levels in freshwater eggs for better egg quality. Mg, P, VA and VE should also be given as sturgeon food supplements. [ABSTRACT FROM AUTHOR]

The study objective was to explore the effects of noise generated by a 2000 hp containership on the reaction of Chinese sucker Myxocyprinus asiaticus. The noise was played back for various durations (1, 2, 4, 8, 24 h) at 142.8 dB re 1 μPa. Immediately after the noise exposure, hearing abilities of the fish were tested using the auditory evoked potential ( AEP) protocol and compared with the response to a control group with no noise exposure. After 1 h noise exposure no significant differences were found compared to control fish; however, significant auditory threshold shifts began to occur at 800 Hz after 2 h of noise exposure. After 24 h of noise exposure, significant auditory threshold shifts were found at all tested frequencies (100-3000 Hz) when compared to control fish. Recoveries were also measured until the auditory thresholds returned to the hearing levels of the control fish. Auditory thresholds of all Chinese suckers fully returned to control levels within 96 h of recovery time. The results indicate that ship noise exposure can lead to threshold shifts in Chinese sucker and that these threshold shifts are temporary, referred to as temporary threshold shift ( TTS). [ABSTRACT FROM AUTHOR]