Age of European silver eels during a period of declining abundance in Norway
Age of European silver eels during a period of declining abundance in Norway
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DOI：
10.1002/ece3.6234
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发表时间：
2020-04-12
影响因子：
2.6
通讯作者：
Vollestad, Leif Asbjorn
中科院分区：
文献类型：
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作者：
Durif, Caroline M. F.;Diserud, Ola H.;Vollestad, Leif Asbjorn
欧洲鳗鱼(安圭拉鳗鱼)在其整个活动范围内都处于极度濒危状态。了解未来产卵者(银鳗)的年龄分布对于监测该物种的状况和促进该物种的恢复至关重要。鳗鱼年龄的确定具有挑战性，特别是来自分布区北部的鳗鱼，那里生长缓慢，成熟时的年龄可达30岁或更长时间。挪威IMSA河的鳗鱼自1975年以来一直受到监测，这一参考时间序列被用来评估欧洲一级的种群。20世纪80年代末，通过估计整个清理过的耳石的年龄，分析了该流域的种群动态。然而，在耳石上显示年增量的技术随着时间的推移而发展，有时会产生显著的年龄估计差异。在这项研究中，使用研磨和抛光的方法重新分析了历史耳石数据，而不是读取整个耳石。新的年龄估计比以前的高出很多，有时高达29岁。自20世纪80年代以来，银鳗的平均年龄仅略有增加(从19岁增加到21岁)。这主要是由于较年轻的银鳗(
The European eel (Anguilla anguilla) is critically endangered throughout its range. Knowledge about age distribution of future spawners (silver eels) is essential to monitor the status and contribute to the recovery of this species. Determination of age in anguillid eels is challenging, especially in eels from the northern part of the distribution area where growth is slow and age at maturation can be up to 30 years or more. Eels from the river Imsa in Norway have been monitored since 1975, and this reference time series has been used to assess the stock at the European level. Population dynamics in this catchment were analyzed during the late 1980s by estimating ages on whole cleared otoliths. However, techniques for revealing annual increments on otoliths have evolved over the years sometimes yielding significant differences in age estimates. In this study, the historical otolith data were reanalyzed using a grinding and polishing method rather than reading the whole otolith. The new age estimates were considerably higher than the previous ones, sometimes by up to 29 years. Since the 1980s, mean age of silver eels only slightly increased (from 19 to 21 years in the 2010s). This was mainly due to the disappearance of younger silver eels (