Neraas L P, Spruell P
Wild Trout and Salmon Genetics Laboratory, Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
Mol Ecol. 2001 May;10(5):1153-64. doi: 10.1046/j.1365-294x.2001.01269.x.
Migratory bull trout (Salvelinus confluentus) historically spawned in tributaries of the Clark Fork River, Montana and inhabited Lake Pend Oreille as subadult and adult fish. However, in 1952 Cabinet Gorge Dam was constructed without fish passage facilities disrupting the connectivity of this system. Since the construction of this dam, bull trout populations in upstream tributaries have been in decline. Each year adult bull trout return to the base of Cabinet Gorge Dam when most migratory bull trout begin their spawning migration. However, the origin of these fish is uncertain. We used eight microsatellite loci to compare bull trout collected at the base of Cabinet Gorge Dam to fish sampled from both above and further downstream from the dam. Our data indicate that Cabinet Gorge bull trout are most likely individuals that hatched in above-dam tributaries, reared in Lake Pend Oreille, and could not return to their natal tributaries to spawn. This suggests that the risk of outbreeding depression associated with passing adults over dams in the Clark Fork system is minimal compared to the potential genetic and demographic benefits to populations located above the dams.
洄游型公牛鳟（Salvelinus confluentus）历史上在蒙大拿州克拉克福克河的支流中产卵，并作为亚成鱼和成鱼栖息在彭德奥里尔湖。然而，1952年建造的内阁峡谷大坝没有鱼类洄游设施，破坏了这个系统的连通性。自这座大坝建成以来，上游支流中的公牛鳟种群数量一直在下降。每年，当大多数洄游型公牛鳟开始它们的产卵洄游时，成年公牛鳟会回到内阁峡谷大坝的底部。然而，这些鱼的来源尚不确定。我们使用了八个微卫星基因座，将在内阁峡谷大坝底部采集的公牛鳟与从大坝上游和下游更远处采集的鱼进行比较。我们的数据表明，内阁峡谷的公牛鳟很可能是在上游支流中孵化、在彭德奥里尔湖生长，并且无法回到它们出生的支流中产卵的个体。这表明，与克拉克福克系统中大坝上方种群潜在的遗传和人口统计学益处相比，与成年鱼越过大坝相关的杂交衰退风险极小。
