岱海移殖大银鱼十年总结——第9年才成功第10年突然绝迹原因分析

Introduction of Whitefish ( Protosalanx hyalocranius ) into Daihai Lake: Success in the Ninth Year, Failure in the Tenth Year

岱海渔场１９８７年从太湖引进大银鱼受精卵，当年未见成效。１９８８年再度引进，秋冬开始捕到少量个体。１９８９年仍能捕到大银鱼，并且个体均匀、生长良好，表明已在岱海自行繁殖。此后，开始清野和保护幼鱼，进行人工增殖。１９９５年终于获得渔业生产效益，总计捕捞大银鱼３１０ｔ，创利税１５５０余万元。但１９９６年大银鱼在岱海突然绝迹了，主要原因是拖网生产时间长，船只多，使沉积湖底多年的有机物质大量翻浮起来，底层形成了一个缺氧层，在缺氧的情况下Ｈ２Ｓ、ＮＨ３－Ｎ等有害物质大量产生，致使没有回避能力的大银鱼受精卵在湖底未能发育成活。

Fertilized eggs of whitefish ( Protosalanx hyalocranius ) were introduced into Dahai Lake from Tai Hu Lake by Daihai Hatchery in 1987. No whitefish larvae were found in the lake in the subsequent year. The second introduction of the fish was conducted in 1988, and a few of the fish were caught in the fall of that year. The fact that whitefish with even size and good growth were still caught in 1989 indicated that the animal had produced offsprings in the lake. Since then, multiplication measurements were taken, including elimination of unwanted fishes and protection of the introduced fish larvae. Up to 1995, high fishery benefits were obtained: annual whitefish production of 310 ton and economic profits of 15 500 000 yuan (RMB). In 1996, however, the whitefish disappeared suddenly mainly due to high mortality of its fertilized eggs. It seems that many trawlers operated on the lake for a long period, leading to resuspension of deposits and occurrence of poisonous H 2S, N NH 3 and anoxia at the lake bottom.