Pautzke, the following abstract was for a presentation that Pat Hulett, WDFW fish biologist with the Kalama Resarch Team, gave at the 7th Pacific Coast Steelhead Management meeting in March 2000. By the way, do you know when the wild broodstock program started on the Kalama? Were the first smolts planted in 1998?

Legacy of 30+ Years of Potential Hatchery Stock Introgression on Kalama River Steelhead: Still Wild After all These Years?

Patrick L. Hulett, Washington Department of Fish and Wildlife

Allozyme genetic marking approaches were used in two long-term studies to estimate the reproductive success of non-locally derived stocks of hatchery summer and hatchery winter steelhead spawning naturally in the Kalama River. Results of the recently completed winter-run study yielded results that are qualitatively similar to those from the previously published summer-run study. On a per-spawner basis, natural production by the hatchery steelhead was substantially lower than that of the wild adults, particularly as measured to the returning adult stage of their offspring. The disparity in reproductive success was increasingly pronounced at successive (subyearling, smolt, and adult) life history stages of the offspring. These results are believed to reflect genetic differences between the wild and hatchery stocks, though some influence from environmental effects cannot be ruled out. In turn, the genetic components of the reproductive performance differentials likely include both non-local stock source and domestication selection effects.

Continued natural spawning by those non-local stocks poses both ecological and genetic risks to wild steelhead. Significant smolt production by hatchery spawners (with relatively poor adult returns) may hinder wild stock productivity through competition for limited resources in the stream. Moreover, the wild stocks are at risk of genetic introgression because of temporal and spatial overlap in spawning of hatchery and wild stocks. However, genetic analyses from recent brood years demonstrate discrete stock structure among the four spawner groups. This suggests that wild stocks have substantially resisted genetic swamping effects despite 30+ years of potential interbreeding with hatchery stocks. Specific mechanisms responsible for maintenance of stock structure are not well understood, but likely include cumulative effects of both the variable degrees of reproductive isolation between hatchery and wild fish and low rates of adult production from hatchery fish. Importantly, these results DO NOT demonstrate that genetic introgression has not occurred, only that the degree of introgression has not (as of yet) lead to homogenization of hatchery and wild stocks.

Because of continued concerns for ecological and genetic risks to the wild stocks, adults from the genetically dissimilar hatchery stocks are no longer permitted access to the principal spawning areas in the Kalama (upstream of a barrier falls and trap at Rkm 17). In addition, new research has been initiated to evaluate stock performance and the wild stock conservation merits of using locally derived wild broodstock as a source for hatchery steelhead production.

* on the web at
http://home.gci.net/~trout/steelhead/2000abstract.htm