DIVERGENCE IN FIRST GENERATION HATCHERY FISH

1) Reisenbichler, R. R. 1994. Genetic factors contributing to declines of
anadromous salmonids in the Pacific Northwest. D. Stouder, Peter Bisson,
and R. Naiman (eds.) In: Pacific Salmon And Their Ecosystems. Chapman
Hall, Inc.


"Gene flow from hatchery fish also is deleterious because hatchery
populations genetically adapt to the unnatural conditions of the hatchery
environment at the expense of adaptedness for living in natural streams.
This domestication is significant even in the first generation of hatchery
rearing."
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2) Jonsson, Bror, and Ian A. Fleming. 1993. Enhancement of wild salmon
populations. G. Sundnes ed.) Human impact on self-recruiting populations,
an international symposium. Kongsvoll, Norway, Tapit, Trondheim, Norway.

"Thus, the use of supplementation to enhance populations should be
carefully considered, even when only a single generation boost to a
population seems warranted.
" Differences were evident for hatchery Atlantic salmon relative to wild
salmon, with common genetic backgrounds, in breeding success after a single
generation in the hatchery. Hatchery females averaged 80% of the breeding
success of wild females and hatchery males averaged 65% of the breeding
success of wild males."
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3) Reisenbichler, RR. 1996. The risks of hatchery supplementation. The
Osprey. Issue 27. June 1996.

"Available data suggest progressively declining fitness for natural rearing
with increasing generations in the hatchery. The reduction in survival from
egg to adult may be about 25% after one generation in the hatchery and 85%
after six generations. Reductions in survival from yearling to adult may be
about 15% after one generation in the hatchery, and 67% after many generations."
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4) Verspoor, Eric. 1988. Reduced genetic variability in first generation
hatchery populations of Atlantic salmon. Can. J. Fish. Aquat. Sci. Vol. 45,
1988.

"Mean heterozygosity and number of alleles per locus were positively
correlated with effective number of adults (N) used to establish the
hatchery groups and averaged 26 % and 12 % lower, respectively, than wild
stocks. The observations are consistent with a loss of genetic variability
in the hatchery salmon from random drift caused by using small numbers of
salmon for broodstock.
"More hatchery groups appeared to be monomorphic than did wild stocks.
"Hatchery samples were 50% larger than those from the wild introducing a
bias in favor of detecting alleles in the hatchery groups compared with the
wild stocks. Thus the differences is probably underestimated.
"There is a loss of alleles in the hatchery groups with lower Ne (effective
breeding population numbers) values.
"Theory suggest that most (>99%) genetic variability will be preserved if
Ne of the broodstock is > 50.
"Losses of genetic variability can occur even in the first hatchery
generation if numbers of fish used for broodstock are not sufficient. The
average reductions in variability detected here are the same as those found
in salmon maintained in hatcheries for a number of generations. Stahl found
levels of heterozygosity to be 20% lower in Swedish hatchery salmon."
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5) Waples, Robin. Dispelling some myths about hatcheries. February 1999.
The American Fisheries Society. Fisheries Vol. 24. No. 2.

"In the Tucannon River in southeastern Washington, a (hatchery)
supplementation program for the depressed run of spring chinook salmon (O.
tshawytscha) was initiated in the mid-1980s. Founded with local broodstock,
this program aims to maintain genetic integrity of the natural population
and has a strong research and evaluation component. In spite of these
efforts, data for the early 1990s showed that, compared to the natural
adults, returning hatchery fish were younger, were smaller for the same age,
and had lower fecundity for the same size (Burgert et al. 1992). The
underlying causes of these somewhat surprising phenotypic changes are not
known; however, even if the changes were entirely an environmental response
to hatchery conditions, they still would represent a significant
single-generation reduction in productivity of the population."

You could take DNA samples from wall mounts that were done prior to the hatcheries going in, if you could find them.

Skyrise makes an interesting point - aren't those predominently Skamanias in the Great Lakes?

You have to be careful not lump all of the salmonids into the same category. RA3 has a point, Skamanias do not reproduce well, so if introduced into a small wild population, may have an impact on the run. However, in systems with larger summer-run populations, or larger river systems, the Skamanias have little affect because they do not have the opportunity to spawn with wild fish. I believe this to be the case on the Kalama, in which there appear to be separate genetic lines for wild and hatchery fish. The wilds spawn in different parts of the watershed. Deer Creek on the Stilliguamish as well. These summer-runs spawn exclusively in the tributary of the stilly, and the summer-runs have never found them to interact.

The reason everyone found the high schoolers study unusual is because wild and hatchery coho salmon have mixed in the past, and have resulted in decreased survival and fitness of wild stocks. Thats why they started clubbing hatchery coho in Oregon, which recently created a ruckuss in the news. Perhaps the same spatial mechanism is at work in the Chehalis, keeping the hatchery and wilds separate.

Skamanias are indeed planted in the Great Lakes, but natural reproduction of steelhead has not been that great. The species that has taken off in the Great Lakes is our good ole pink salmon. Pinks were introduced accidently back in the 50s, I believe, and from this accidental introduction into Lk. Superior (??), they have established runs in all 5 Great Lakes. They even have both odd and even runs, somewhere along the way, some pinks came back as two-salts instead of one-salts and established the off-year run.

Although genetic studies are important to flesh out just how hatchery interactions affect wild fish, I think its just as important to study the 'where' and 'whens' of spawning, looking at the size and complexity of the watershed, size and timing of each of the runs, genetic integrity of the hatchery stock, how they're planted, etc. If it were a simple question, the solution would be simple. But since you have these seemingly conflicting results on many different watersheds, there isn't a singular solution. You could ban all hatcheries, but this would not be agreeable to me, and a lot of other folks who value their fishing opportunities, nor is it supported by the existing science, nor is it politically acceptable. You could do more genetic studies, but understand, because of the many different variables that also exist, and differing levels of impacts on different river basins (from none at all to substantial), it would take freighter full of money to flesh things out.

I think the State Legislature could get a clue from this high schoolers study. This person produced for free, worth while results, while WDFW's budget continues to get slashed lower and lower. Its backward thinking--funding keeps getting tighter the farther we move into crisis with salmon and steelhead stocks.

[ 06-12-2001: Message edited by: obsessed ]