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I would like to extend the discussion about straying in the context of ongoing activities between Indian tribal fishery agencies and the State. Both groups have been working on jointly developing a policy on wild salmonids that addresses straying, gene flow, and other genetic issues. The issue of salmon straying has important genetic implications for the conservation of wild stocks, harvest management, and hatchery production. Hatchery production, usually using non-local stocks, has been used to meet harvest management objectives (harvest augmentation). In contrast, the chief goal of hatchery supplementation, like that used for Snake River stocks, is to restore or increase productivity of wild stocks. Increasingly, the occurrence of declines in wild stock abundance has prompted consideration of alternative rebuilding strategies, with much focus on strategies involving supplementation. This move to emphasize natural productivity and to maintain or increase harvestable surpluses reflects a transition from the context that most fishery managers have been working within for many decades. It is important to keep in mind that salmon management, with all of its inherent complexity, is now undergoing a major transition.

The key factor when considering the genetic effects of straying is maladaptive gene flow, not just the physical presence of non-local or hatchery-origin fish in natural populations. However, direct measures of gene flow are at best difficult to obtain, and the number of strays into a spawning population may be all that we have as surrogate estimates of gene flow. Given that we need better ways of estimating the actual numbers of non-local fish spawning in the wild, we must focus on reproductive overlap between hatchery fish spawning in the wild and wild fish. Estimates of this overlap will provide one of the best surrogate measures of actual gene flow in the absence of direct measures, and thus overlap is a key part of State and tribal discussions on wild salmonids. 

Several assumptions about life-history patterns and gene flow have been made during our wild-salmonid policy discussions. One is that some level of straying and gene flow occurs naturally between wild populations, but just how much and under what circumstances is uncertain. Another assumption is that human-produced elevated rates of natural straying and unintended straying from non-local hatchery sources are undesirable because of the potential loss of genetic variability within and among populations, and because outbreeding may decrease fitness and productivity. More information on the effects of outbreeding depression, as Gary Graves pointed out, is urgently needed to assist in the development of rational management policies. Another important assumption in the evolving policy is that various management strategies can be used to increase homing or to decrease rates of straying. Several state monitoring and evaluation programs are under way to understand better the causes and effects of straying. 

With respect to general guidelines in formulating Washington's wild salmon policy, the intent of the State and tribal fishery agencies is to manage gene flow to maintain genetic diversity and to conserve local adaptations, productivity, and evolutionary potential. More information is needed on the means to achieve these rather abstract goals. The underpinnings of our wild salmonid policy are clearly set out in legislation passed by the Washington State Legislature in 1993, which directs the State to ensure that department actions and programs are consistent with the goals of rebuilding wild stock populations to levels that permit commercial and recreational fishing opportunities (Washington State Legislature 1993, p. 73). This general directive and the Department's response to developing a wild salmonid policy under the State Environmental Policy Act (public review and comment) and in collaboration with tribal managers is intended to allow flexibility in responding to the specific requirements of different watersheds, regions, and species. A fundamental conceptual difficulty has been to decide whether a fitness-based approach or a diversity-based approach is more appropriate; to date we have leaned toward the latter. Issues related to fitness would be indirectly addressed.

In general, our diversity-based approach requires first a description of genetic diversity within and between populations of each species. Part of this need was met in the wild salmon and steelhead stock inventory (WDF 1993). In addition, we are attempting to describe the hierarchical components of genetic, life-history, and ecological diversity within each species. Our approach and methods are similar to those used by NMFS to make determinations regarding Evolutionary Significant Units (ESUs). However, as a practical, conservative approach, we will identify smaller units to manage for genetics, population status, and maintenance. Secondly, we expect to manage for specific levels of gene flow (e.g., reproductive overlap) between hierarchical population units; that is, we intend to manage unnatural gene flow between population units. This includes, for example, gene flow resulting from stock transfers and other practices, and from overlap resulting from hatchery fish that escape harvest and spawn with wild fish. Surrogate measures of gene flow will be required.

We are aware that reproductive isolation between subpopulations can occur in different ways. Some groups of fish may spawn at the same time, but in different places. Others may spawn at different times, but in the same area. Again, accommodating these subtleties of life-history patterns and migratory and spawning behavior is important. Although simply measuring the number or percentage of hatchery fish straying into a particular stream may be feasible, it will lead to imprecise estimates of gene flow. A better approach would be to estimate overlap, and to target the amount of allowable overlap between population units to be scaled to the relative genetic similarity between hatchery and wild fish in a particular watershed. We are, however, still uncertain as to what levels of gene flow or surrogate measures (e.g., overlap) should be allowed between hatchery and wild fish under various circumstances and are hoping the panel will help clarify the options and their corresponding risks. For our policy approach to be implementable and therefore successful, we need to be able to measure and to monitor suitable parameters; we are aware that various theoretical predictions are possible, but we need to have practical tools so we can monitor progress toward meeting policy objectives. Once the policy has been completed, implementation plans will consider a broad range of strategies. Monitoring plans will include a systematic review of hatchery practices to identify and activate improvements needed to achieve compliance with wild salmonid policy goals.

Washington State Legislature, House Committee on Fisheries and Wildlife. 1993. Second Engrossed Substitute House Bill 1309, p. 69-74. 1993 final legislative report: Fifty-third Washington State Legislature, 1993 regular session, first special session, Washington State Legislature, Olympia, WA, 340 p. (Available from House Office of Program Research and Senate Research Center, Olympia, WA 98501.)

Washington Department of Fisheries (WDF), Washington Department of Wildlife (WDW), and Western Washington Treaty Indian Tribes (WWTIT). 1993. 1992 Washington State salmon and steelhead stock inventory (SASSI). Wash. Dep. Fish Wildl., Olympia, 212 p. and 5 regional volumes. (Available from Washington Department of Fish and Wildlife, 600 Capitol Way N., Olympia, WA 98501-1091.) 

Comment: Marta Nammack: I noticed that both Gary Graves and Steve Leider say that the burden of proof should be on the scientists to show that theoretical concepts are important. I think the burden of proof should be shifted to the proponents of hatchery programs to show that their activities do not influence wild populations. 

Steve Leider: Point well taken.

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