HATCHERIES CHANGE SALMONIDS IN ONE GENERATION





By  Bill M. Bakke, Director


Native Fish Society





	The fish agencies and tribes are excited about using hatchery technology to


rebuild wild, native salmon and steelhead.  They advocate using native brood


stock in the hatchery and increasing the survival of juvenile fish for


release into the river too boost what they call "natural production."


	The hatchery advocates' premise assumes that hatcheries do not select for a


hatchery type fish which perform well in the artificial hatchery


environment, but do not survive well in the natural environment.  However,


the scientific literature on this issue seems to disagree.  While the fish


agencies and tribes have not been willing to fund research on hatchery


effects on natural salmonid populations, some research is, nevertheless,


beginning to accumulate.  


	The following quotes are taken from a few studies and comments based on


studies that have looked at the issue of using hatcheries to rebuild wild,


native salmonid populations.  These  scientific works reach a disturbing


conclusion: the hatchery can cause changes in the first generation that


affect survival.  





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."