象山港黄姑鱼增殖放流效果评估及增殖群体利用方式优化

摘要

Nibea albiflora is one of the commercially important fish stocks that is depleted in Xiangshan Bay, a semi-enclosed tidal inlet located on the east coast of Zhejiang Province, East China. To rebuild the depleted stock and increase the fishermen’s incomes, hundreds of thousands of hatchery juvenileN. albiflora are released into the bay annually. However, the effectiveness of the stock enhancement program has not yet been evaluated. In this study, we evaluated the recaptured yield and abundance of spawners originating from the hatchery-released juve-niles ofN. albiflorain Xiangshan Bay with a mark-recapture experiment and classical fishery models. We propose a method to prioritize the fishing strategy for the released stock. In September 2011, 11 055 5-month-old hatch-ery-reared juvenileN. albiflora were tagged with a scutcheon tag and released into Xiangshan Bay. The tagged fish were collected by local commercial fisheries during the two months following their release. The natural and fishing mortality of the hatchery-released individuals was 0.51/a and 1.31/a, respectively. In the fishery scenario, the stock enhancement program would generate 737 kg of recapture yield, and the direct input-output cost ratio would be 1 : 3.99. The number of hatchery-released juveniles surviving to sexual maturity would be approximately 554, which would contribute to the spawning stock and help restore the depletedN. albiflorastock. The effectiveness ofN. albiflora stock enhancement is strongly dependent on the level of fishing effort, and the appropriate reduc-tion in the fishing effort would benefit both the recapture yield and the abundance of spawners originating from hatchery-released juvenileN. albiflora. If the fishing mortality declined to 0.46/a, or 36% of the estimated value, the total recapture yield would reach 1045 kg and the abundance of spawners originating from the hatch-ery-released juveniles would be 4413. These two values are 41.49% and 326.90% higher, respectively, than those in the current fishery scenario. In conclusion, theN. albiflora enhancement program in Xiangshan Bay shows good ecological performance and economic efficiency. An appropriate reduction in the fishing effort is essential to im-prove its effectiveness.%以回捕渔获重量和对繁殖群体的补充能力为评价指标,借助标志放流−回捕实验,利用模型模拟分析方法,定量评估浙江象山港黄姑鱼(Nibea albiflora)的增殖放流效果；同时,结合其增殖目标定位,探索构建生态高效的增殖群体利用方式。研究结果表明,象山港黄姑鱼增殖群体的捕捞死亡系数为1.31,在该捕捞强度下,11055尾增殖放流鱼苗可产生737 kg回捕渔获收益,同时还向增殖水域补充了554尾初次性成熟个体,增殖放流活动在一定程度上起到了修复象山港黄姑鱼资源、促进渔民增产增收的效果。结果表明,捕捞强度过大是制约象山港黄姑鱼增殖放流功效发挥的重要因素,捕捞死亡系数应降至0.46,同批次黄姑鱼增殖放流所能提供的回捕渔获重量和性成熟个体尾数可分别较现行捕捞强度提升41.49%和326.90%。综上述,象山港黄姑鱼增殖放流的生态和经济功效较为显著,合理降低对增殖群体的捕捞强度是进一步提升其增殖放流效果的必要措施。