Abstract The release of piscivorous fishes is considered crucial to alleviate eutrophication and fish miniaturization, as well as to develop sustainable fisheries management strategy for Yangtze lakes. In order to promote the stock enhancement programme of a new released piscivorous fish species Culter mongolicus, growth, recapture rates, reproduction and impact of size-at-release for hatchery-reared juveniles were evaluated in three Yangtze shallow lakes during a five-year period. C. mongolicus displayed important growth capability with a body weight reaching commercial size (> 500 g) during the second released year and about 1500 g in the third year. However, a sharp decline of growth appeared quickly after several years of releasing, indicating possible issue of density-dependent growth caused by over-stocking. The recapture rates for one-month-old juveniles were less than 5%, but increased to more than 20 % when one-year-old fingerlings were selected as release size. Gonad examination and catch analysis showed that released juveniles could not succeed in building the recruitment stock due to over-fishing. Thus hatchery-reared juveniles should be released annually. Management actions that prioritize the release of fewer but larger fingerlings will improve the recapture rate and subsequent economic benefit. A new stock enhancement strategy that changes the present release-catch cycle from two years to one was proposed accordingly.

中文翻译：

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蒙古鲢种群增殖：长江湖泊生长、捕捞和释放规模评估

摘要 放流鱼类对缓解富营养化和鱼类小型化以及制定长江湖泊可持续渔业管理战略至关重要。为促进新放生的肉食性鱼类蒙古鲢的种群增殖计划，在五年期间对三个长江浅水湖中孵化场饲养的幼鱼的生长、再捕获率、繁殖和释放时的大小的影响进行了评估. C. mongolicus 表现出重要的生长能力，第二年体重达到商业规格（> 500 g），第三年达到约 1500 g。然而，在释放几年后，增长迅速出现急剧下降，表明可能存在因库存过剩而导致的密度依赖增长问题。当一岁的一岁的鱼片被选择为释放尺寸时，单月大少年的重新估计率小于5％，但增加到20％以上。性腺检查和捕获量分析表明，由于过度捕捞，释放的幼鱼无法成功建立补充种群。因此，孵化场饲养的幼鱼应每年释放一次。优先放流较少但较大的鱼种的管理措施将提高回收率和随后的经济效益。相应地提出了一种新的种群增强策略，将当前的放捕周期从两年改为一年。性腺检查和捕获量分析表明，由于过度捕捞，释放的幼鱼无法成功建立补充种群。因此，孵化场饲养的幼鱼应每年放飞一次。优先放流较少但较大的鱼种的管理措施将提高回收率和随后的经济效益。相应地提出了一种新的种群增强策略，将当前的放捕周期从两年改为一年。性腺检查和捕获量分析表明，由于过度捕捞，释放的幼鱼无法成功建立补充种群。因此，孵化场饲养的幼鱼应每年释放一次。优先放流较少但较大的鱼种的管理措施将提高回收率和随后的经济效益。相应地提出了一种新的种群增强策略，将当前的放捕周期从两年改为一年。