Authors
Shawn R. Narum
Madison S. Powell
Rolf Evenson
Bill Sharp
André Talbot
Report Reference
#06-1
Publication Date
Spring
2006 in
North American Journal of Fisheries Management
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Microsatellites Reveal Population
Substructure of Klickitat River Native Steelhead and Genetic Divergence
from an Introduced Stock
Abstract |
| Determining
fine-scale genetic diversity and structure is critical for the conservation
and management of populations, especially those under heavy anthropogenic
influence. We analyzed 446 individuals at nine microsatellite loci
to determine the local population structure of naturally produced
steelhead Oncorhynchus mykiss and genetic differentiation
from introduced hatchery strain steelhead in the Klickitat River of
the Pacific Northwest. We detected significant genetic structure among
steelhead in various tributaries to the Klickitat River; the most
divergent population was located above a waterfall that acts as a
partial upstream migration barrier (average pairwise FST=0.13;
P<0.0001). Analysis of mixtures indicated an estimate of six to
seven genetically distinct populations of naturally reproducing steelhead
in this river system. The hatchery strain appears to remain genetically
distinguishable from native stocks (average pairwise FST
of 0.078 with P<0.0001), as only 4.0% of naturally produced steelhead
had their most likely assignment to the hatchery strain. These results
indicate that the genetic integrity and variation of native Klickitat
River steelhead have been maintained despite repeated hatchery introductions
and that the potential is high for restoring this threatened population.
Further, this study suggests that hierarchical analyses of mixtures
to identify distinct populations in a watershed are a valuable method
for directing management of reproductively isolated populations. |
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