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By Angela Bolton, Russian River Coho Recovery Workgroup
Institute for Fisheries Resources
In the work of restoring the coasts badly damaged salmon runs, sometimes you have to take emergency room action just to keep the patient alive long enough to do any good.
A new captive broodstock program for coho is underway in California, sponsored by PCFFA through the Institute for Fisheries Resources (IFR), which serves coastal fishing communities. Initiated in 2001, the IFR program on the Russian River, in Californias Sonoma County, is one part of a coordinated effort between federal, state and local agencies and non-profit partners to recover coho salmon within the Central California Coast Evolutionarily Significant Unit (ESU). The Russian River stocks are particularly depressed, with populations in recent years down to a few hundred individuals in a river that was once a major producer of salmon, but which for decades has been badly polluted and nearly dewatered by upper river and streamside urban development, reservoirs and agricultural withdrawals. Under the circumstances, there was little choice but to resort to an emergency broodstock program to buy enough time to work toward better flows in the river and to clean up its problems with pollution, both of which are now also underway.
Captive broodstock programs are becoming an increasingly important component of species preservation and restoration of imperiled salmonid populations in major river systems. The Endangered Species Act (ESA) recognizes artificial propagation as a potential conservation tool, and since the early 1990s salmonid captive broodstock technology has grown from a promising though untested concept to an approach that is currently being employed for numerous Pacific and Atlantic salmon stocks. Within the Columbia Basin, captive broodstock programs have been established for Redfish Lake sockeye salmon, and Salmon River (Idaho Department of Fish and Game, IDFG), Grande Ronde River (Oregon Department of Fish and Wildlife, ODFW), Tucannon River spring-run chinook salmon in the Snake River and the Wenatchee River (White River) spring-run chinook salmon. Outside of the Columbia River Basin and in addition to the coho program on the Russian River in central California, other captive brood programs have been established for Sacramento River winter-run chinook salmon, White River (coastal Washington) spring-run chinook, Dungeness River spring-run chinook and Hood Canal coho salmon.
While captive broodstock programs are relatively new, the idea of supplementing wild salmon populations with artificial production goes back decades. Hatcheries for augmenting salmon production have been operating in California since the 1870s, when the federal government sent Dr. Livingston Stone west to look for a likely candidate, one amenable to captive rearing, to replace the Atlantic salmon, in decline on the East Coast even then.
Since then, of course, hatchery practices have changed commensurate with the growing understanding of the importance of using locally adapted genetic stock. However, any method that uses artificial propagation to increase natural production of a population is called supplementation, so captive broodstock methods are only a subset of a range of possible supplementation methods. The power and promise of the captive broodstock approach is the potential to maintain the genetic diversity of a depressed population and to provide a meaningful boost to population demographics quickly.
Two programs, both in operation since the early 1990s, have observed increases in the number of adult salmon returning to spawn. In California, the numbers of returning Sacramento River winter-run chinook had declined from 117,800 in 1967 to less than 200 by the early 1990s, resulting in a threatened species designation in 1990, and endangered listing in 1994. The recovery plan included development of a propagation program that released over 150,000 juvenile fish in 1998, a program pioneered by PCFFAs late past-President, Nat Bingham. Adult contributions from these juveniles have been documented in the ocean fishery and in escapement monitoring in the upper Sacramento River.
In Idaho, the National Marine Fisheries Service listed Snake River sockeye salmon as endangered under the ESA in 1991, with the last 16 known members of this stock returning to Redfish Lake over the course of the following ten years. After capturing and rearing all of these fish for captive broodstock, hundreds of thousands of progeny were produced and released, such that between 1999 and 2002, over 300 adult progeny of captively reared fish returned to spawn representing an almost 20-fold amplification of the number of wild fish that were observed during the 1990s.
These two programs exemplify the two captive broodstock strategies being utilized throughout the Pacific Northwest to get the fish back into the wild and once again self-reproducing: rearing populations to maturity in hatcheries and releasing their first and/or second generation progeny into ancestral lakes or streams at one or more juvenile life stages; or, rearing broodstock to adulthood in captivity then releasing them back into their natural habitats to spawn naturally. Both programs have sought to protect the fish in captive propagation from catastrophic loss or high mortality by dividing the captive population between separate facilities, where one portion of the population is reared in saltwater, in keeping with the normal anadromous fish life cycle. This acts as an extra bit of insurance against accidents or disease.
The current program on the Russian River adopts the first rearing-and-release strategy, whereby first generation progeny will be released as fingerlings in the fall, thereby avoiding the potential for summer mortality but allowing for the fish to experience the most time in the wild, thus potentially reducing the chances of selection for domesticated traits. At present, however, Russian River program fish will not be subject to saltwater rearing, due in part to the lack of an appropriate facility and funding.
While the California chinook and Idaho sockeye programs have exhibited some success, with the chinook program posting a three-year adult spawner replacement rate for 2001 that was higher than the target rate identified in the NMFS 1997 Biological Opinion, captive propagation on its own will rarely, if ever, constitute a complete recovery program. The sponsors of the new program on the Russian River acknowledge this, and are working to address the factors of decline that caused the coho population to reach its current status, where this year juvenile coho were observed in only one tributary out of more than thirty surveyed. Ultimately the answer to the problem of damaged salmon runs must lie in cleaner rivers with more water in them and the removal of blockages to fish passage to and from good spawning and rearing habitat.
However, restoring a whole river takes time, and often means years pushing against many other interests and priorities. Extinction, however, takes only the loss of salmon over three or four years, and unfortunately lasts forever. Taking emergency steps to protect the genetic integrity of a run while the bigger issues are being dealt with often makes very good sense. The loss of any salmon runs key genetic stocks that evolved over millions of years would be irreplaceable, and could potentially jeopardize the entire ESU. To prevent that from happening, life support salmon broodstock and gene conservation programs such as this one serve a vitally important function so we had better learn to do it right!
Angela Bolton is the Coordinator of the Russian River Coho Recovery Workgroup, a program organized through the Institute for Fisheries Resources (IFR), PCFFAs affiliate fisheries research and conservation organization. Angela can be reached at IFRs Southwest Regional Office, PO Box 29196, San Francisco, CA 94129-0196, (415)561-3474 or by email to: email@example.com. For more information about the Institute for Fisheries Resources and its various marine fisheries restoration and conservation programs, go to IFRs web page at: www.ifrfish.org.
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