RECOVERY SCIENCE REVIEW PANEL, (RSRP)

Northwest Fisheries Science Center, Seattle Washington

August 30-September 1, 2004

The impact of hatchery fish on the status of listed Pacific salmon

Dr. Joe Travis, Dr. Russell Lande, Dr. Marc Mangel, Dr. Ransom Myers, Dr. Pete Peterson, Dr. Mary Power, Dr. Dan Simberloff

Introduction:

One of the major factors affecting the status of listed Pacific salmon is the potential negative effect that hatchery fish exert on populations of wild fish. Ironically, while many hatchery programs were designed to accelerate population recovery of wild fish and stabilize their numbers, there is evidence that many supplementation programs have the opposite effect. To be sure, there is considerable variation among programs in the nature and magnitude of the effort to enhance natural populations and in their effects to date. But the bulk of the evidence indicates that, on the whole, hatchery fish are not equivalent to wild fish, genetically or phenotypically. Despite optimism about improvements in hatchery practices,…hatchery environments differ substantially from natural environments and create fish that differ from their wild counter parts in development trajectories that affect morphology, behavior, physiological responses, and life history. Whether these phenotypic differences are genetically based through domestication…or are induced by early environmental exposure,….they represent inevitable, significant phenotypic alterations. Inbreeding between hatchery fish and wild fish can, through numerical swamping, reduce the fitness of wild fish, which can contribute to the decline of the wild population.

The RSRP is concerned that including hatchery fish in listing decisions could greatly jeopardize the mandate of long-term recovery of natural, self-sustaining populations. This concern led us to focus our meeting of August 30-September 1, 2004 on an examination of the interactions between hatchery and wild fish, how hatchery fish may be affecting the populations of wild fish, the scientific issues surrounding efforts at habitat compensation and restoration that involve hatchery fish, and the scientific inconsistencies created by the proposed hatchery policy.

Quotes From The Text Of The Report:

“We believe that the loss of fitness in the wild is an inevitable consequence of adaptation to hatcheries and evidence suggests that this loss can occur even in the initial generations of breeding stock.

“Rigorous experimental evaluations of the effects of hatchery augmentation are critical because they offer the strongest evidence for testing the long-held assumption that hatchery augmentation is effective and beneficial for wild populations. This assumption remains untested because, despite widespread hatchery augmentation, there have been few attempts to exploit hatchery releases in an experimental fashion-meaning treatment and control-to evaluate the effects of augmentation.

“Relative fitness of hatchery fish declines regularly with the number of generations in culture…fitness is lost in excess of 20% per generation.

“If listing, and especially delisting criteria count hatchery spawned as well as wild fish, Holly Doremus (Professor of Law, University of California-Davis) warned the panel that it will be very difficult to ascertain what recovery means. The major motivation for hatcheries throughout their long history has been to compensate fisheries for production lost to uses of water and watersheds that impair fish habitat. If hatchery spawned fish are counted as part of the ESU, or DPS, for listing and delisting, there may be a tendency to redefine the environment of salmon stocks to include artificial propagation facilities. (Note: NMFS reclassified dams as a natural feature of the salmon ecosystem in the 2004 Biological Opinion for the Columbia River.)

“Despite recent improvements in the practices of some hatcheries…hatcheries will never produce salmonids with the same evolutionary potential as those spawned in the wild. A perpetual metapopulation between wild and hatchery salmonid populations is not an acceptable recovery for listed salmonids under the ESA. Fish removed from nature to propagate in hatcheries always constitute a loss to the evolutionarily significant natural population. For listed salmonids, this must be done only as a last resort to boost numbers to the point at which the natural population can become self-sustaining, and these hatchery conservation programs need defined termination dates or criteria.

“Hatcheries managed for harvest production must be viewed as potential or actual threats to listed wild stocks, and must be managed to limit impacts on wild populations so as to not violate the ESA.

“Although most attention focused on the ESA has been on its goal preventing extinction, the Act has a second mandate: to achieve sufficient self-sustaining wild populations of listed species to ensure their survival in nature.

“We remain extremely concerned about scientific implications of the proposed hatchery policy (NMFS 2004), which dictates that when hatchery fish are sufficiently similar to wild fish they should be included in the same ESU as the wild fish.

“Even when substantial data exist to support similarity with respect to quasi-neutral molecular genetic markers, in the absence of information on morphology, behavior and life history, it is not valid to conclude that there are no adaptive differences between hatchery and wild fish.

“In the absence of substantial information on potentially adaptive differences between specific hatchery fish and the wild fish in an ESU, a highly precautionary approach to the assessment of their similarity ought to be taken. The wisdom of a precautionary approach is suggested by well known behavior differences, e.g. in feeding and predator avoidance, the recent finding of greatly diminished brain size in hatchery fish, and by several reports of substantially reduced fitness in hatchery fish. Yet in all cases with extant wild populations(s), even those with no data on either quasi-neutral molecular markers or potentially adaptive traits or fitness, a determination of the degree of similarity was made. This does not appear justified to us: we believe that in the majority of cases there is insufficient evidence on which to make a reliable assessment of similarity, and most of the specific determinations should have been “unknown” or “data deficient.” Alternatively, the precautionary principle, combined with the expectation that hatchery influence is usually detrimental to wild fish populations, could have been used to exclude hatchery fish from an ESU in specific cases with inadequate information to make a strongly supported determination of similarity. The scientific justification for including hatchery fish in an ESU in such cases is extremely weak.

“Even clear evidence of minimal genetic differences between wild and hatchery fish should be interpreted cautiously. In many situations, e.g. for some ESUs listed as threatened or endangered under the ESA, hatchery strays constitute a substantial or overwhelming fraction of fish spawning in the wild. In such situations, even though genetic and fitness differences between wild and hatchery fish may not be statistically significant, it is possible, or even likely, that adaptation to the hatchery environment has reduced the fitness of fish spawning in the wild, and if hatchery influences continue unabated, evolution of the ESU will be substantially impeded or altered in direction, to the detriment of its long-term viability. For this reason, the RSRP suggests that in such situations hatchery fish, either should not be included as part of the ESU, or if included in the ESU should not be used to justify delisting from the ESA. This highlights the importance of conducting experiments on the genetic and ecological effects of hatchery fish on wild fish, as recommended in previous RSRP reports.

“The Hatchery and Broodstock Summaries and Assessments classified the degree of similarity only on a 1 to 4 scale based on the available information. Final determination of the degree of similarity for including hatchery fish in a listed ESU was made by the fisheries management branch of NMFS rather than by the science branch. This sets an inappropriate precedent for what is fundamentally a scientific determination.

“Myers et al (2004) suggested that hatchery fish should never be included in an ESU. The main justification for this point of view is that hatchery fish experience a different environment than wild fish during their early life and inevitably undergo natural selection in a different direction than wild fish. Adaptation to the hatchery environment is similar to the well-understood process of domestication, which in the presence of gene flow from hatchery to the wild, generally reduces the fitness of the wild population and their ability to adapt to future changes in the natural environment. Except for extreme cases when a temporary conservation hatchery is necessary to prevent extinction of a small…and declining wild population, hatchery fish should be regarded as impeding the future evolution of an ESU. For this reason Myers et al. (2004) recommended that NMFS scientists should revisit the definition and application of the ESU concept. In the context of restoring wild self-sustaining populations of salmon, placing increased emphasis on the future adaptation and continued persistence of an ESU in a changing environment would justify the categorical exclusion of hatchery fish from most ESUs.

“Our suggestions in previous paragraphs are consistent with Waples’ (1991) arguments that hatchery fish should not be included in an ESU based solely on origin of the hatchery stock and that a burden of proof must be met for determining similarity to wild stock(s). The Artificial Propagation policy (NMFS 1993) likewise stated that hatchery fish should be excluded from an ESU if they are different genetic lineage, have undergone major changes, or if there is substantial uncertainty. To the panel it appears that the proposed hatchery policy directly violates the thinking of leading NMFS scientists.

References

National Marine Fisheries Service. 2004. Endangered and threatened species: proposed policy on the consideration of hatchery-origin fish in Endangered Species Act Listing Determinations for Pacific salmon and steelhead. Fed. Reg. 69:31354-31359.

National Marine Fisheries Service. 1993. Interim policy on artificial propagation of Pacific salmon under the Endangered Species Act. Fed. Reg. 58: 17573-17576.

Myers, R.A., S.A. Levin, R. Lande, F.C. James, W.W. Murdoch and R.T. Paine. 2004. Hatcheries and endangered salmon. Science 303:1980.

Waples, R.S. 1991. Pacific salmon, Oncorhyncus spp., and the definition of “species” under the Endangered Species Act. Marine Fisheries Review 53:11-21.