from "factors contributing to the decline of steelhead"
August 1996 National Marine Fisheries Service
B. Manmade Factors
1. Artificial Propagation
In 1993, over 81 million juvenile salmonid hatchery fish were released into the Snake and
Columbia River system above Bonneville Dam (Columbia Basin Fish and Wildlife Authority
1994). Juvenile steelhead have accounted for about 15 percent of these releases, or about 12
million juveniles (Columbia Basin Fish and Wildlife Authority 1994). Juvenile steelhead
hatchery releases average about 2.5 million below Bonneville Dam since 1987 (Columbia Basin
Fish and Wildlife Authority 1994). The Snake River system has accounted for the majority of
steelhead hatchery production in areas above Bonneville Dam, averaging about 5 million
juveniles per year since 1980 (Columbia Basin Fish and Wildlife Authority 1994). During the
period from 1978 to 1987, the following steelhead hatchery production occurred in the western
United States: Washington at 6,782,000, Idaho at 5,372,000, Oregon at 4,537,000, California
at 2,304,000, and Alaska at 62,000 fish per year (Light 1987). A total of 24,605,000 steelhead
smolts on average are produced each year in these four western states.
Non-native steelhead stocks have historically been introduced as broodstock in hatcheries and
widely transplanted in many coastal rivers and streams. Altukhov and Salmenkova (1986) have
shown that anadromous salmonids transferred to other watersheds rarely persist for more than
two generations without repeated artificial propagation. Withler (1982) showed that there has
been no successful case of establishing a new run of anadromous salmonids by transplanting
stocks anywhere along the Pacific Coast. Fisheries agencies within the states of Washington,
Oregon, Idaho and California, along with other organizations, have transplanted non-native
steelhead stocks throughout their respective states within this past century (Bryant 1994, Busby
et al. 1996).
Many concerns exist regarding the impacts of artificial propagation on wild stocks of salmon.
49
Competition which can occur among hatchery and native adults for spawning sites and food,
may lead to decreased production. Hatchery may outnumber wild fish and monopolize available
spawning habitat when wild stocks are small and hatchery supplementation occurs. Fleming
and Gross (1992) stated that the negative effect of such competition can be magnified by the fact
that naturally spawning hatchery stocks have lower spawning success than do wild fish.
Steward and Bjornn (1990) found that hatchery stocks may also produce fewer smolts and
returning adults. Nielsen (1994) found the introduction of hatchery reared coho salmon into the
Noyo River, California, led to displacement of wild cohorts from their usual microhabitats and
shifts in their foraging behavior. Stempel (1988) concluded that competition might be occurring
in the mainstem of the Klamath and Trinity rivers among hatchery and wild salmonids, resulting
in low survival of both.
Juvenile steelhead which have been derived from non-native, hatchery broodstock may stray and
interact with native populations. Altukhov and Salmenkova (1986) reported that when non-native
hatchery strays spawn in the wild, young fish with some non-native genes may result.
Studies conducted in areas of the Pacific Coast have found that juvenile salmonids produced
from stray hatchery fish and hatchery-wild hybrids have relatively low survival rates compared to
native fish (Chilcote et al. 1986, Riesenbichler and McIntyre 1977). Waples (1991), Hindar et
al. (1991), and Steward and Bjornn (1990) found that the impact of stock transfers increases
dramatically if non-native salmonids are planted on top of wild populations for several
generations. When this method of transfer occurs, Altukhov and Salmenkova (1986) found a
loss of local adaptations which may lead to extirpation of that local stock.
Genetic changes in hatchery stocks of Pacific salmonids have been documented and models have
recently been constructed by Waples (1990a,b) and Waples and Teel (1990) to aid in
understanding the consequences of these changes. Steward and Bjornn (1990) noted that large
differences in the genetic structure of wild and hatchery stocks may potentially lead to lower
survival rates. Steward and Bjornn (1990) also reported that supplementation with hatchery
stocks can have differing effects depending on the size of the wild population. Shapovalov and
Taft (1954) noted an inverse correlation between the number of downstream migrants and adult
50
returns, implying that low intraspecific competition increases oceanic survivorship of
downstream migrants.
Crowded conditions in hatcheries can create favorable environments for many disease
organisms. Introduction of exotic stocks can also introduce a new disease into a wild
population. The ability of a wild stock to cope with an introduced disease is reduced if the
stock's genetic variability has been reduced through selection or genetic drift (Allendorf and
Phelps 1980).
The capture of broodstock may also adversely impact small or declining wild populations due to
pre-spawning mortality during capture or transport, differential viability of gametes in artificial
situations, disease, and artificial selection. Verspoor (1988) noted that wild broodstock typically
contribute little genetic diversity to subsequent generations of hatchery fish. Taking more wild
fish for broodstock in an attempt to overcome these problems in hatchery stocks may ultimately
increase risks to wild populations.
The relatively low number of spawners needed to sustain a hatchery population can result in high
harvest-to-escapement ratios in waters where regulations are set according to hatchery
production. This practice can lead to over-exploitation and reduction in size of wild populations
coexisting in the same system. For example, in a declared "hatchery management area" in
British Columbia, harvest rates on coho salmon are as high as 95 percent (Hilborn 1992). This
is sustainable only because of the most successful hatchery stocks, and, as a result, wild stocks
have declined (Hilborn 1992).
Available research indicates that interactions between non-native and wild stocks may have
contributed to the decline of this species across its range. More recent hatchery practices, such
as utilizing native broodstocks and limiting native and hatchery fish interactions through
temporal or geographic means, may reduce negative impacts to wild stocks. However,
hatcheries may palliate the widespread loss and destruction of habitat, concealing the real
problems facing anadromous resources (Goodman 1990, Hilborn 1992, Meffe 1992).
More.....
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." _____________________________________________________ 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." _______________________________________________________ 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." _______________________________________________________ 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." __________________________________________________ 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."
[ 05-09-2003, 12:52 AM: Message edited by: rob allen ]
August 1996 National Marine Fisheries Service
B. Manmade Factors
1. Artificial Propagation
In 1993, over 81 million juvenile salmonid hatchery fish were released into the Snake and
Columbia River system above Bonneville Dam (Columbia Basin Fish and Wildlife Authority
1994). Juvenile steelhead have accounted for about 15 percent of these releases, or about 12
million juveniles (Columbia Basin Fish and Wildlife Authority 1994). Juvenile steelhead
hatchery releases average about 2.5 million below Bonneville Dam since 1987 (Columbia Basin
Fish and Wildlife Authority 1994). The Snake River system has accounted for the majority of
steelhead hatchery production in areas above Bonneville Dam, averaging about 5 million
juveniles per year since 1980 (Columbia Basin Fish and Wildlife Authority 1994). During the
period from 1978 to 1987, the following steelhead hatchery production occurred in the western
United States: Washington at 6,782,000, Idaho at 5,372,000, Oregon at 4,537,000, California
at 2,304,000, and Alaska at 62,000 fish per year (Light 1987). A total of 24,605,000 steelhead
smolts on average are produced each year in these four western states.
Non-native steelhead stocks have historically been introduced as broodstock in hatcheries and
widely transplanted in many coastal rivers and streams. Altukhov and Salmenkova (1986) have
shown that anadromous salmonids transferred to other watersheds rarely persist for more than
two generations without repeated artificial propagation. Withler (1982) showed that there has
been no successful case of establishing a new run of anadromous salmonids by transplanting
stocks anywhere along the Pacific Coast. Fisheries agencies within the states of Washington,
Oregon, Idaho and California, along with other organizations, have transplanted non-native
steelhead stocks throughout their respective states within this past century (Bryant 1994, Busby
et al. 1996).
Many concerns exist regarding the impacts of artificial propagation on wild stocks of salmon.
49
Competition which can occur among hatchery and native adults for spawning sites and food,
may lead to decreased production. Hatchery may outnumber wild fish and monopolize available
spawning habitat when wild stocks are small and hatchery supplementation occurs. Fleming
and Gross (1992) stated that the negative effect of such competition can be magnified by the fact
that naturally spawning hatchery stocks have lower spawning success than do wild fish.
Steward and Bjornn (1990) found that hatchery stocks may also produce fewer smolts and
returning adults. Nielsen (1994) found the introduction of hatchery reared coho salmon into the
Noyo River, California, led to displacement of wild cohorts from their usual microhabitats and
shifts in their foraging behavior. Stempel (1988) concluded that competition might be occurring
in the mainstem of the Klamath and Trinity rivers among hatchery and wild salmonids, resulting
in low survival of both.
Juvenile steelhead which have been derived from non-native, hatchery broodstock may stray and
interact with native populations. Altukhov and Salmenkova (1986) reported that when non-native
hatchery strays spawn in the wild, young fish with some non-native genes may result.
Studies conducted in areas of the Pacific Coast have found that juvenile salmonids produced
from stray hatchery fish and hatchery-wild hybrids have relatively low survival rates compared to
native fish (Chilcote et al. 1986, Riesenbichler and McIntyre 1977). Waples (1991), Hindar et
al. (1991), and Steward and Bjornn (1990) found that the impact of stock transfers increases
dramatically if non-native salmonids are planted on top of wild populations for several
generations. When this method of transfer occurs, Altukhov and Salmenkova (1986) found a
loss of local adaptations which may lead to extirpation of that local stock.
Genetic changes in hatchery stocks of Pacific salmonids have been documented and models have
recently been constructed by Waples (1990a,b) and Waples and Teel (1990) to aid in
understanding the consequences of these changes. Steward and Bjornn (1990) noted that large
differences in the genetic structure of wild and hatchery stocks may potentially lead to lower
survival rates. Steward and Bjornn (1990) also reported that supplementation with hatchery
stocks can have differing effects depending on the size of the wild population. Shapovalov and
Taft (1954) noted an inverse correlation between the number of downstream migrants and adult
50
returns, implying that low intraspecific competition increases oceanic survivorship of
downstream migrants.
Crowded conditions in hatcheries can create favorable environments for many disease
organisms. Introduction of exotic stocks can also introduce a new disease into a wild
population. The ability of a wild stock to cope with an introduced disease is reduced if the
stock's genetic variability has been reduced through selection or genetic drift (Allendorf and
Phelps 1980).
The capture of broodstock may also adversely impact small or declining wild populations due to
pre-spawning mortality during capture or transport, differential viability of gametes in artificial
situations, disease, and artificial selection. Verspoor (1988) noted that wild broodstock typically
contribute little genetic diversity to subsequent generations of hatchery fish. Taking more wild
fish for broodstock in an attempt to overcome these problems in hatchery stocks may ultimately
increase risks to wild populations.
The relatively low number of spawners needed to sustain a hatchery population can result in high
harvest-to-escapement ratios in waters where regulations are set according to hatchery
production. This practice can lead to over-exploitation and reduction in size of wild populations
coexisting in the same system. For example, in a declared "hatchery management area" in
British Columbia, harvest rates on coho salmon are as high as 95 percent (Hilborn 1992). This
is sustainable only because of the most successful hatchery stocks, and, as a result, wild stocks
have declined (Hilborn 1992).
Available research indicates that interactions between non-native and wild stocks may have
contributed to the decline of this species across its range. More recent hatchery practices, such
as utilizing native broodstocks and limiting native and hatchery fish interactions through
temporal or geographic means, may reduce negative impacts to wild stocks. However,
hatcheries may palliate the widespread loss and destruction of habitat, concealing the real
problems facing anadromous resources (Goodman 1990, Hilborn 1992, Meffe 1992).
More.....
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." _____________________________________________________ 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." _______________________________________________________ 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." _______________________________________________________ 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." __________________________________________________ 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."
[ 05-09-2003, 12:52 AM: Message edited by: rob allen ]
