Hey sorry Jer, but there are indeed stocks genetically adapted and unique to specific basins. Straying fish are natures way of expanding the geographic range of the species, and for the most part, strays are less successful because they are not as adapted to different watersheds as natives, but occasionally they do take hold. Particularly in those watersheds with declining stocks. With each subsequent generation, their genes and level of adaptation more closely resemble the native fish.
In looking at that article you have to be sure to note that they're dealing with salmon, not steelhead. Unlike steelhead, it seems many hatchery salmon stocks are very adept at spawning successfully in rivers if they aren't taken out of the system. Not as successful as natives, but with declining stocks left, right, and center, they do take hold and mix their genes with native populations, potentially weakening gene pools.
With most hatchery steelhead stocks originating from the Chambers Creek winter stock and Skamania summer stock, these fish are largely unsuccessful at reproducing in the wild. The Chambers Creek fish have been manipulated into a fairly unnatural early returning stock. Summer steelhead in general do not have a naturally large presence in western Washington and are not that suited to summer time conditions in streams west of the cascades. These are probably the reasons for their lack of widespread success at reproducing in the wild, which is good.
This level of hatchery manipulation has not occurred with salmon stocks, so they mix away. I am for hatchery supplementation of salmon stocks to increase fishing opportunities and relieve the stress on some of our native stocks, but hatchery practices should strive to take these fish out of the basin before spawning--i.e., 100% marking, and release and collection at a terminal facility.
[ 04-18-2001: Message edited by: obsessed ]
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