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首页> 外文期刊>ICES Journal of Marine Science >Development of wild Atlantic salmon stocks in the rivers of the northern Baltic Sea in response to management measures
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Development of wild Atlantic salmon stocks in the rivers of the northern Baltic Sea in response to management measures

机译：根据管理措施在波罗的海北部河流域开发野生大西洋鲑鱼种群

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摘要

Since 1980, the abundance of wild Atlantic salmon has been monitored by means of catch records, adult counts, electrofishing and smolt trapping in six rivers flowing into the northern Baltic Sea. River abundance (spawners, parr and smolts) was compared with implemented large-scale and river-specific management measures and with natural factors potentially affecting abundance. Since the 1980s, the wild stocks have recovered in a synchronous cyclical pattern. The recovery occurred mainly in two jumps, first a sudden increase dating back to around 1990 and a second sharp rise in the late 1990s. River abundance of young salmon commonly rose about 10-fold and approached the previously estimated production capacity in some of the rivers. This positive development may be explained by a decline in fishing pressure together with covarying natural factors influencing survival and growth. The offshore fishery started to decline at the time of the first increase, while the reduction in the total allowable catches together with seasonal restrictions on the coastal fishery strengthened the second increase. Improved natural conditions seem to have increased both survival and escapement during the first rise. Spawners producing the second rise were the offspring of the spawners of the first rise. The outbreak of the M74 mortality syndrome among alevins reduced the abundance of several year-classes that hatched during the first half of the 1990s. In most rivers, the fraction of older and female fish in the spawning run has increased over the period, thereby increasing the reproductive capacity of the populations. No distinct effects of variations in river-specific management regimes were observed. Instead, the results emphasize the role of fisheries management in the open sea as well as in coastal waters, and also of non-human factors in controlling overall abundance of wild salmon in northern Baltic rivers.
机译：自1980年以来，通过捕获记录，成年数量，电钓鱼和在流入北波罗的海北部的六条河流中诱捕鲑鱼的方式对野生大西洋鲑鱼的数量进行了监测。比较了河流的丰富度（产卵场，幼鱼和熏鲑）与已实施的大规模和针对特定河流的管理措施以及可能影响河流丰富度的自然因素。自1980年代以来，野生种群以同步周期性的方式恢复。复苏主要发生在两次跳跃中，第一次是在1990年左右突然增加，第二次是在1990年代后期急剧上升。河中幼鲑的丰富度通常上升约10倍，并接近某些河流先前估计的生产能力。捕捞压力下降以及影响生存和生长的各种自然因素可以解释这种积极的发展。第一次增加时，近海渔业开始下降，而总允许渔获量的减少以及沿海渔业的季节性限制加剧了第二次增加。自然条件的改善似乎在第一次上升时增加了生存和逃逸。产生第二次上升的产卵者是第一次上升的产卵的后代。 Alevins中M74死亡率综合症的爆发减少了1990年代上半年孵化的若干年班的数量。在大多数河流中，产卵期的成年鱼类和雌性鱼类比例在此期间有所增加，从而提高了种群的繁殖能力。没有观察到在特定河流管理制度中变化的明显影响。相反，结果强调了渔业管理在公海和沿海水域中的作用，以及非人为因素在控制波罗的海北部河流域野生鲑鱼的总体丰度中的作用。

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