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首页> 外文期刊>ICES Journal of Marine Science >Post-smolt survival of Baltic salmon in context to changing environmental conditions and predators
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Post-smolt survival of Baltic salmon in context to changing environmental conditions and predators

机译：在环境条件和捕食者变化的背景下，波罗的海鲑鱼的熏鲑后生存

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The survival of Baltic salmon Salmo salar during the first year at sea (post-smolt stage) has declined since the beginning of the 1990s. In this analysis, we complement previous studies on possible causes of this decline by considering a suite of environmental parameters, potential change in predation pressure, and post-smolt growth. Marine survival estimates were found to be negatively correlated with temperature, indicating that warming conditions have not favoured survival. Survival was also found to be positively correlated with dissolved oxygen levels and regionally related to shifts in salinity. These relationships were further studied in context to the potential predation on post-smolts by one of the main piscivores in the Baltic, Eastern Baltic cod (Gadus morhua callarias). Concomitant with changes in environmental conditions, Baltic cod has changed its latitudinal range, moving northward in the Baltic, possibly in response to warming conditions. These changes lead us to hypothesize that predation pressure on salmon may have increased in recent years as cod has now occupied habitats used by salmon post-smolts during their southward feeding migrations. This predation may have been intensified as a result of anoxic conditions in the central basin by concentrating predation interactions in coastal waters and/or the upper water column typically occupied by salmon post-smolts. Indicators of post-smolt growth were applied to test the alternate hypothesis that mortality is growth-mediated; these indicators lacked a time series trend, which supports the contention that shifting predation pressure rather than feeding opportunities is responsible for the decline in post-smolt survival in Baltic salmon.
机译：自1990年代初以来，波罗的海鲑鱼Salmo salar在海上第一年（熏香后）的存活率下降了。在此分析中，我们通过考虑一系列环境参数，捕食压力的潜在变化以及后软体动物的生长来补充先前关于这种下降的可能原因的研究。发现海洋生存估计与温度呈负相关，表明变暖条件不利于生存。还发现存活率与溶解氧水平呈正相关，与盐度变化呈区域性正相关。在波罗的海东部波罗的海鳕（Gadus morhua callarias）的主要食食动物之一捕食mol后，进一步研究了这些关系。随着环境条件的变化，波罗的海鳕鱼改变了其纬度范围，可能在波罗的海向北移动，这可能是由于气候变暖所致。这些变化使我们推测，近年来鲑鱼的捕食压力可能会增加，因为鳕鱼现在已经占据了鲑鱼在南方的迁徙迁徙过程中所使用的栖息地。通过集中在沿海水域和/或通常由鲑鱼后软体动物占据的上水柱中的捕食相互作用，可能由于中央盆地缺氧条件而加剧了这种捕食。蜕皮后生长的指标用于检验死亡率由生长介导的另一种假设。这些指标缺乏时间序列趋势，这支持了这样的论点，即捕食压力的变化而不是觅食机会是造成波罗的海鲑鱼蜕皮存活率下降的原因。

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