Upstream Salmon and Society in the Pacific Northwest (1996) / Chapter Skim
Currently Skimming:
12 Hatcheries
12 Hatcheries
Pages 302-323
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 302... ...
In this century, the intended goal of most hatchery programs has been mitigation. Mitigation aims to lessen the immediate impact of human actions through definition of a "socially acceptable" altered state (Christie et al.
|
From page 304... ...
PROBLEMS ASSOCIATED WITH HATCHERY PRACTICES Traditional approaches of hatchery programs have imposed different types of biological problems on salmon populations, including demographic risks; genetic and evolutionary risks; problems due to the behavior, health status, or physiology of hatchery fish; and ecological problems. One or more of those problems might have affected either the populations that a hatchery program aimed to rebuild, other populations with which they interact, or both (Allendorf and Ryman 1987, Gharrett and Smoker 1991, Kapuscinski 1991, Riddell 1993b, Allendorf and Waples in press)
|
From page 305... ...
Population Identity and Within-Population Variability Numerous studies involving comparisons of hatchery and wild populations have yielded strong evidence that traditional hatchery practices have caused losses of genetic variability between and within anadromous-salmon populations (e.g., Allendorf and Ryman 1987, Riddell 1993a, Allendorf and Waples in press)
|
From page 306... ...
reviewed evidence suggesting that hatchery fish stray at a higher rate than naturally reproduced fish, but there are few data sets on straying of wild salmon (Quinn 19931. Within-population genetic diversity will be eroded if the effective population size (No)
|
From page 307... ...
after consecutive collections of hatchery gametes primarily from early-returning adults. A second source of domestication selection is altered selection pressures due to differences between the natural environment and the hatchery culture resulting from physical conditions or operational practices in the hatchery.
|
From page 308... ...
The practice of making artificial matings-now the dominant hatchery method is a serious concern because it disrupts natural patterns of sexual selection with negative implications for fitness of hatchery fish in natural environments. Sexual selection is an important part of the evolution of most vertebrate species.
|
From page 309... ...
In that situation, genetic adaptation to the hatchery environment is greatly enhanced because of the lack of exposure of the population to natural selection in natural environments. The risk of domestication is less certain in most Pacific salmon hatchery programs, where only part of a fish's life cycle is exposed to hatchery selection pressures and the rest is exposed to a complex suite of selection pressures in freshwater and marine environments, including selection pressure by natural environmental conditions, such as predation in the ocean, and by human-induced environmental conditions, such as dam passage, stream habitat alterations, altered stream fish communities (e.g., Reznick et al.
|
From page 310... ...
The lesson from that study is that any efforts to use hatchery fish to rebuild a naturally reproducing population should consider the ecological implications of and perhaps seek to avoidchanges in time of spawning and size at release for hatchery and naturally reproduced fish.
|
From page 311... ...
Dramatically increased vulnerability to infectious disease has been demonstrated in some natural populations, such as the African cheetah, which have experienced demographic declines and dramatic reductions in overall genetic variability due to human activities. The implication for rehabilitation of anadromous salmon is clear: it is critically important to maintain the remaining genetic diversity within and between populations to conserve diversity for genes that are involved in disease defense.
|
From page 312... ...
Incomplete smoltification of some hatchery fish is also a major cause of concern (e.g., Shrimpton and Randall 1992~. Research in the Columbia River basin suggests that poorly smelled hatchery fish lack strong downstream migration behavior, so they reside longer in stream habitats, while fully smelted fish tend to migrate downstream with little or no delay (Bradford and Schreck 1989, 1990; Snelling et al.
|
From page 313... ...
Ecological Problems Hatchery programs have given virtually no attention to the ecological context into which fish are released. Yet some ecological factors, such as carrying capacity of proximate and distant stream environments for various juvenile life stages and density-dependent interactions within and between species, can exert substantial control over the fate and impacts of released fish.
|
From page 314... ...
ROLES OF HATCHERIES IN THE FUTURE OF SALMON What roles do hatchery programs have in the rehabilitation of Pacific anadromous salmon? Answering that question implies agreement about the values human place on features of the environments in which Pacific salmon and steelhead occur.
|
From page 315... ...
Regarding natural largescale controls, natural productivity cycles of the Pacific Ocean will control the maximum possible abundance of hatchery returns by forcing a low value during periods of low productivity and allowing increased values during periods of increased productivity. The role of hatcheries is affected by society's choice between continual high human inputs to salmon ecosystems and rehabilitation of their natural regenerative capacity.
|
From page 316... ...
Under the option of rehabilitation, the role of hatcheries would be much more limited and refined than their historical role because rehabilitation of the natural regenerative capacity of an ecosystem requires congruence of each human intervention with natural structures and processes of genetics, evolution, and ecology. An important building block of natural structures is the pattern of genetic diversity between and within anadromous salmon populations, and an important building block of natural processes is the evolution of salmon populations.
|
From page 318... ...
Temporary hatcheries could be extended in principle if habitat damage or loss cannot be reversed in a reasonable period and people are not prepared to give up the salmon populations associated with the habitats. To be compatible with the goal of rehabilitation, this extension requires that negative impacts of hatchery fish on other naturally spawning populations be kept negligible.
|
From page 319... ...
CONCLUSIONS Despite some successes, hatchery programs have been partly or entirely responsible for detrimental effects on some wild runs of salmon. The loestdocumented detrimental effects are loss of wild populations because hatchery fish swamp a mixed fishery, which encourages fishery managers to set exploitation rates that cause overfishing of natural populations, and loss of natural patterns of genetic variability between and within populations.
|
From page 320... ...
In addition, cumulative effects of all the hatchery programs in a given region have not been evaluated. Potential effects on the genetic diversity and ecology of wild populations have been ignored, although this is beginning to change.
|
From page 321... ...
Hatcheries should be dismantled, revised, or reprogrammed if they interfere with a comprehensive rehabilitation strategy designed to rebuild wild populations of anadromous salmon to sustainability. It makes the most sense to test the ability of hatcheries to rehabilitate populations whose natural regenerative potential is severely constrained by both short-term and long-term limitations on rehabilitation of freshwater-habitats.
|
From page 322... ...
All hatchery programs should adopt a genetic-conservation goal of maintaining genetic diversity that exists between and within hatchery and naturally spawning populations. All agencies involved in management of anadromous salmon should recognize that achievement of population-rebuilding goals will be jeopardized without concurrent adoption of a genetic-conservation goal.
|
From page 323... ...
Coordination should be improved among all hatcheries in release timing, scale of releases, operating practices, and monitoring and evaluation of individual and cumulative hatchery impacts, including a coastwide database on hatchery-wild fish proportions and numbers. Given the differences among the five regions in the status of environmental conditions that affect Pacific salmon populations, a different suite of interventions under adaptive management should be assembled for each region, and each intervention in a region should be treated as an experiment.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.