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首页> 外文期刊>ICES Journal of Marine Science >Stock assessment of eels in the Baltic: reconciling survey estimates to achieve quantitative analysis
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Stock assessment of eels in the Baltic: reconciling survey estimates to achieve quantitative analysis

机译：波罗的海鳗鱼种群评估：调和调查估计数以实现定量分析

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The data from two scientific surveys, where eel is part of the catch, have been studied to assess trends in recruitment and escapement to and from the Baltic. Abundance of juvenile eel was monitored in the Sound, between Sweden and Denmark, from 1992 to 2002. The total natural recruitment of new eels was estimated under the assumption that the number of juvenile eels observed in the surveys represented an accumulation of eels migrating into the Baltic. To assess the total recruitment, the stocking by imported glass eels, or transplanted juveniles from outside the Baltic, was added. Fish larvae monitoring at a nuclear power plant in the Kattegat gave an index of glass eel abundance which was well correlated with glass eel monitoring in the Sound. This was used to extrapolate the recruitment time-series to the full period from 1981 to the present. The main conclusions from the analysis were: (i) the recruitment to the Baltic region, including the contribution from stocking, has declined by 95% between 1981 and 2012. (ii) The stocking of glass eel and bootlace eel has been of the same order of magnitude as natural recruitment, averaging 25-30% of the total supply of glass eel to the Baltic, with a decreasing trend with time. (iii) The total landings in the Baltic countries have ranged from 5 to 15% of the estimated survival without anthropogenic mortality. This proportion has been stable and independent of a large decrease in potential escapement.
机译：对鳗鱼是渔获物一部分的两次科学调查的数据进行了研究，以评估往返波罗的海的招募和逃逸趋势。从1992年到2002年，在瑞典和丹麦之间的桑德海峡对幼鳗的数量进行了监测。在调查中观察到的幼鳗数量代表迁移到该地区的鳗鱼的积累的前提下，估计了新鳗的自然招募总量。波罗的海。为了评估总招募量，增加了进口玻璃鳗或从波罗的海以外地区移植的幼鱼的种群。在Kattegat一家核电厂的鱼幼虫监测给出了玻璃鳗丰度的指数，该指数与Sound中的玻璃鳗监测密切相关。这是用来将征聘时间序列推算到1981年至今的整个时期。分析的主要结论是：（i）从1981年到2012年，波罗的海地区的招募工作，包括放养的贡献下降了95％。（ii）玻璃鳗和and鱼的放养量相同数量级为自然补充，平均占波罗的海鳗鱼总供应量的25％至30％，并且随着时间的推移呈下降趋势。 （iii）波罗的海国家的总着陆量为无人为死亡率的估计生存率的5％至15％。这个比例是稳定的，与潜在擒纵机构的大幅度减少无关。

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