Lower fitness of hatchery and hybrid rainbow trout compared to naturalized populations in Lake Superior tributaries
Lower fitness of hatchery and hybrid rainbow trout compared to naturalized populations in Lake Superior tributaries
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与苏必利尔湖支流的归化种群相比，孵化场和杂交虹鳟鱼的适应性较低
作者：
Lisa M. Miller;T. Close;A. Kapuscinski
我们已经证明，与最近引入的孵化场种群相比，归化的淡水型虹鲑鱼种群具有早期生存优势，而这两个品系之间的杂交导致了近亲繁殖的抑制。我们测试了这样一个假设，即在明尼苏达州苏必利尔湖支流的孤立河段，驯化鲑鱼和孵化鲑鱼的后代，以及相互杂交的后代，从苗种到1岁以上的存活都是一样的。在第一个夏天，在四个比较中的三个(两条溪流和两年的放养)中，归化雌性的后代的存活率显著高于孵化雌性的后代。拥有整个归化的基因组，而不仅仅是归化的母亲，对于第一个冬天的生存非常重要。与两个纯交种相比，归化后代在存活到1+岁时表现优于所有其他后代，杂交种的存活率有所降低，但处于中等水平。在多年和溪流的平均情况下，与归化雌性的杂交后代的存活率为0.59，正反交后代的存活率为0.37，孵化后代的存活率为0.21。我们的结果表明，归化的虹鲑鱼更好地适应了明尼苏达州苏必利尔湖支流的条件，因此它们的表现优于孵化场繁殖的品系，就像许多本地鲑鱼种群的表现优于孵化场或移植的鱼一样。继续放养孵化场的鱼可能会与维持归化种群的管理目标相冲突。
We have documented an early life survival advantage by naturalized populations of anadromous rainbow trout Oncorhynchus mykiss over a more recently introduced hatchery population and outbreeding depression resulting from interbreeding between the two strains. We tested the hypothesis that offspring of naturalized and hatchery trout, and reciprocal hybrid crosses, survive equally from fry to age 1+ in isolated reaches of Lake Superior tributary streams in Minnesota. Over the first summer, offspring of naturalized females had significantly greater survival than offspring of hatchery females in three of four comparisons (two streams and 2 years of stocking). Having an entire naturalized genome, not just a naturalized mother, was important for survival over the first winter. Naturalized offspring outperformed all others in survival to age 1+ and hybrids had reduced, but intermediate, survival relative to the two pure crosses. Averaging over years and streams, survival relative to naturalized offspring was 0.59 for hybrids with naturalized females, 0.37 for the reciprocal hybrids, and 0.21 for hatchery offspring. Our results indicate that naturalized rainbow trout are better adapted to the conditions of Minnesota's tributaries to Lake Superior so that they outperform the hatchery‐propagated strain in the same manner that many native populations of salmonids outperform hatchery or transplanted fish. Continued stocking of the hatchery fish may conflict with a management goal of sustaining the naturalized populations.