The Lower Snake River Compensation Program is a hatchery program consisting of 23 fish-rearing facilities and satellite stations designed to mitigate for the loss of salmon (Oncorhynchus spp.), steelhead, and rainbow trout (O. mykiss) caused by the construction of four dams on the lower 250 km of the Snake River. The U.S. Fish and Wildlife Service (USFWS) administers and funds the program, and state and tribal agencies operate the hatcheries and conduct hatchery evaluations. The first facility, the McCall Hatchery in Idaho, began operating in 1980, and the Lookingglass Hatchery in Oregon (Fig. 1) began in 1982, so in terms of salmon generation times (about 4-5 years for chinook salmon), the program has been in operation a short time. I would like to focus on the Lookingglass Fish Hatchery Spring Chinook Salmon Mitigation Program, and Richard Carmichael will talk about the Lyons Ferry Fall Chinook Salmon Mitigation Program. The activities of these programs led, in part, to this workshop on the effects of straying.

The Lookingglass Fish Hatchery Program was designed to produce about 1.4 million spring-run chinook salmon smolts to return about 9,070 spring-run chinook salmon adults to the Grande Ronde and the Imnaha Rivers. The hatchery is operated by the Oregon Department of Fish and Wildlife and uses two stocks of fish: a non-native Rapid River stock, and a native stock from the Imnaha River. Fish from the Rapid River stock are currently released from the hatchery into Lookingglass Creek in the Grande Ronde Basin, whereas the Imnaha stock is released into the Imnaha River after acclimation at the facility on the Imnaha River. In previous years, portions of the Rapid River stock and Carson River stock maintained in the Lookingglass Hatchery were released into the Upper Grande Ronde River, Wallowa River, Catherine River, and into Lookingglass Creek itself.

The release of Rapid River stock as well as Carson River stock has resulted in an extremely high incidence of straying in the Grande Ronde Basin. In some years and at some localities, stray hatchery fish represented 35-100% of the fish found in a particular area. Most recent spawning-ground surveys revealed a considerable amount of straying, as summarized for 1990-93 in Table 1. Estimates of escapement are also shown. For example, in 1990, stray hatchery fish constituted an estimated 46.2% of the spawners in the Minam River, 77.8% in the Wenaha River, 40% in the Lostine River, 100% in Catherine Creek, and 50% in the Grande Ronde River. In 1992, the amount of straying was particularly high, probably because of low water levels that may have prevented access to some spawning areas. In 1993, straying was somewhat lower, but still over 45% in all populations.

Because of the concern over these high rates of straying into local natural populations, we plan to end the use of the Rapid River and Lookingglass Creek hatchery strains when local endemic stocks become available through a captive broodstock program. Such a reduction, however, seriously affects our responsibilities to tribal and governmental recovery programs for the Grande Ronde Basin. We are caught between two judicial directives: the Lower Snake River Compensation Plan and the Endangered Species Act, on the one hand, which call for fish production to mitigate losses caused by hydropower development, and on the other the influence of these programs on endangered populations of spring-run chinook salmon listed under the Endangered Species Act. The USFWS, as well as other agencies, recognizes the responsibility to protect wild and endemic populations of salmon. The regional office of the USFWS wrote a vision document in 1991 to assess the status of natural populations of salmon throughout the region and to improve the information base for wild salmon populations. As a result of this effort, we are assessing the effects of hatcheries and their potential effects on naturally spawning populations.

Table 1. Estimated percentage of carcasses identified as hatchery fish in the Grande Ronde River Basin, 1990-93 (based on coded wire tags, physical marks, and scales analysis).

We are now developing plans to establish captive brood stocks and captive rearing of local fish, but have several unanswered questions. What are the appropriate populations to use in a captive program? Could we use, for example, Lostine River fish, which would most likely stray into the nearby Minam and Wenaha Rivers? Is it necessary to develop several different captive broodstocks for release into specific rivers? How should broodstocks be chosen and how long should they be used? What are acceptable short- and long-term straying rates? Since straying will likely always occur, can we infuse genes from the Minam and Wenaha salmon populations into hatchery populations to insure against adverse effects of one-way gene flow? Many natural populations may be lost in the near future, and we need guidelines for our programs.

Although the problem of straying is important, the low escapement into some of these rivers is cause for more immediate concern. Many marginal populations may go to extinction in the next few years, and for many of us the problem of straying is not the highest item on a list of priorities. Over the short term, we are looking for guidelines to prevent the loss of these valuable, but imperiled, populations.

Discussion

Question: Bill Bakke (Washington Trout): You stated that you have a conflict in terms of your mitigation programs. Could you explain why you used non-native stocks in the Lower Snake River Conservation River Program, at least for the Grande Ronde?

Answer: Ed Crateau: At the time we began our program, few endemic stocks were available to us. It was an emergency, and we thought we could not get a program started with the few wild fish that remained. We wanted to jump-start the program, so we chose Rapid River fish to start the program. We now realize this may have been a mistake, but at the time our primary responsibility was for mitigation, to increase the number of returning adults. Preservation of wild populations was not a high priority at the time. We used Rapid River fish in 1980 and again in 1987. We used Carson River fish in 1982 and again in 1986, but we also tried to use adults that returned to Lookingglass Creek in years they were available. The Lookingglass stock, itself, is a mixture of local fish and returns from Rapid River releases. The Lookingglass/Carson stock is a mixture of fish from those two sources.

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