Initial evaluation of the release programme for Dabry's sturgeon (Acipenser dabryanus Dumeril, 1868) in the upper Yangtze River

摘要

This paper evaluates the outcome of the first release programme for Acipenser dabryanus rehabilitation in its natural habitat and focuses specifically on the growth rate of released juveniles, and on the dispersal of the fish after release. To conserve and restore natural recruitment, the conservation propagation programme has released hatchery-reared juveniles annually in the upper Yangtze River. This paper summarized the release activities and analysed post-release monitoring data. From 2010 to 2012, 7030 juveniles aged 1-3years were released in the Shuifu and Yibin reaches of the upper Yangtze River. Incidental catches of 112 samples were recorded during the three-year observation period. Recapture sites were located between Yibin and Chongqing reaches (approximate range of 385km), with 72.3% of the individuals recaptured within 20km from the release site. Incidental catches were mainly in shallow water within 20m of the riverbank. Body weight of the released sturgeon initially declined but this lost weight was soon regained. The low recaptured rate indicates that only a few of the released juveniles were able to survive and settle in the upper Yangtze River. The observed movement patterns suggest a potential additional downstream release site for future consideration to improve the performance of the released fish.