Lack of trophic competition among wild and hatchery juvenile chum salmon during early marine residence in Taku Inlet, Southeast Alaska
Lack of trophic competition among wild and hatchery juvenile chum salmon during early marine residence in Taku Inlet, Southeast Alaska
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阿拉斯加东南部塔库湾的野生和孵化幼年鲑鱼在早期海洋居住期间缺乏营养竞争
DOI：
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发表时间：
2012
影响因子：
1.4
通讯作者：
Bill Smoker
中科院分区：
文献类型：
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作者：
M. Sturdevant;Emily Fergusson;N. Hillgruber;Carl Reese;J. Orsi;R. Focht;A. Wertheimer;Bill Smoker
研究了阿拉斯加东南部Taku湾野生和孵育大马哈鱼（Oncorhynchus keta）早期海洋营养相互作用作为成年野生大马哈鱼产量下降的潜在原因。在2004年和2005年，在入口近岸栖息地（春季）和冰海峡的上层栖息地（夏季），当它们接近阿拉斯加湾时，对洄游在外的幼鲑进行了采样。冷冻鱼用于能量密度测定或保存鱼粮分析，通过耳石上的热标记来识别孵化场种群。我们比较了野生种群和孵化场种群（n = 3123）在不同地点和不同周的摄食强度、日粮、能量密度和大小关系。只有孵化场鱼类摄食强度与鱼类丰度呈负相关。在这两年里，孵化场的大马哈鱼最初比野生鱼更大，能量密度也更高，但在放生后的最初几周内，它们就失去了状态，因为它们适应了以野生猎物为食。在所有入口位置的种群之间的饮食存在差异，但孵化场鲑鱼在近海和浅海栖息地之间没有差异，在那里种群重叠最多。饮食和能量密度在6月下旬趋于一致。因此，如果密度依赖的相互作用影响野生鲑鱼，这些影响一定是非常迅速的，因为冰海峡的幸存者几乎没有表现出差异。本研究还表明，在大沽口附近采用的孵化场放生策略成功地促进了早期空间隔离和猎物分配，从而降低了野生和孵化场鲑鱼种群之间的竞争概率。
Early marine trophic interactions of wild and hatchery chum salmon (Oncorhynchus keta) were examined as a potential cause for the decline in harvests of adult wild chum salmon in Taku Inlet, Southeast Alaska. In 2004 and 2005, outmigrating juvenile chum salmon were sampled in nearshore habitats of the inlet (spring) and in epipelagic habitat at Icy Strait (summer) as they approached the Gulf of Alaska. Fish were frozen for energy density determination or preserved for diet analyses, and hatchery stocks were identified from the presence of thermal marks on otoliths. We compared feeding intensity, diets, energy density, and size relationships of wild and hatchery stocks (n = 3123) across locations and weeks. Only hatchery fish feeding intensity was negatively correlated with fish abundance. In both years, hatchery chum salmon were initially larger and had greater energy density than wild fish, but lost condition in early weeks after release as they adapted to feeding on wild prey assemblages. Diets differed between the stocks at all inlet locations, but did not differ for hatchery salmon between littoral and neritic habitats in the outer inlet, where the stocks overlapped most. Both diets and energy density converged by late June. Therefore, if density-dependent interactions affect wild chum salmon, these effects must be very rapid because survivors in Icy Strait showed few differences. Our study also demonstrates that hatchery release strategies used near Taku Inlet successfully promote early spatial segregation and prey partitioning, which reduce the probability of competition between wild and hatchery chum salmon stocks.