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UCREFRP
UCREFRP Catalog Number
9515
Author
Waples, R. S., G. A. Winans, F. M. Utter and C. Mahnken
Title
Genetic Approaches to the Management of Pacific Salmon
USFW Year
1990
USFW - Doc Type
Fisheries
Copyright Material
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<br />Ii C{ 0 <br /> <br />Waflt~, tf- vt/ <br /> <br />~ <br /> <br />qt:J /) <br /> <br />Genetic Approaches to the Management of <br />. Pacific Salmon! <br /> <br />I <br />Robin S. Waples, Gary A. Winans, Fred M. Utter, ~nd Conrad Mahnken <br /> <br />ABSTRACT <br /> <br />The complex problems involved in managing Pacific salmon (Ollcorhynchus spp.) are largely a consequence of the <br />unusual life history features of these species. The strong homing instinct leads tp the formation of discrete, locally- <br />adapted spawning populations, each of which has the potential to evolve as an ~ndependent evolutionary unit. It is <br />important, therefore, that the genetic consequences of different management pol ides be carefully evaluated. If current <br />management goals (e.g., doubling the abundance of anadromous salmonids in ithe Columbia River basin through <br />increased hatchery production and supplementation of natural populations) are tealized, genetic issues will assume <br />even greater importance in the future. To date, however, genetic concerns have mit been adequately incorporated into <br />the management process. We identify three genetic approaches, primarily based on!easily obtained electrophoretic data, <br />that can provide valuable information on which to base management decisions: (1) 4sing the Genetic Stock Identification <br />method for identifying stocks contributing to oceanic, mixed-stock fisheries. Genetic Stock Identification has several <br />advantages over traditional tagging methods, including cost-effectiveness and easy access to wild as well as hatchery <br />stocks. (2) Monitoring genetic changes in hatchery stocks. Analysis of the nature a~d magnitude of such changes is the <br />best means of identifying stocks in which potentially dangerous levels of inbreed'ng may be occurring. (3) Detecting <br />mixtures of gene pools. The ability to detect hybridization and introgression is nece~sary for an evaluation of the genetic <br />consequences of releasing artificially propagated fish into the wild. . <br /> <br />Introduction <br /> <br />Anadromous Pacific salmon (Oncorhynchus spp.) are <br />such an important resource in the Pacific Northwest <br />that efforts to control production began over a century ago <br />(Mahnken et a1. 1983). In spite of concerted management <br />efforts in recent decades, the abundance of most Pacific <br />salmon species in recent years has been substantially below <br />historical levels (Fredin 1980; Fraidenburg and Lincoln <br />1985), and a number of stocks have been identified that may <br />qualify for protection under the Endangered Species Act <br />(W. Nehlsen, AFS Endangered Species Committee, per- <br />sonal communication). As we near the last decade of the <br />20th century, major new enhancement programs are being <br />considered, with goals as ambitious as a doubling of the <br />run size of anadromous salmonids in the Columbia River <br />basin (NWPPC 1987). Achieving such goals will not be easy. <br />Pacific salmon have proved to be among the most chal- <br />lenging species to manage effectively, primarily as a con- <br />sequence of their unusual life history features. <br /> <br />Spawning in Discrete Freshwater Populations <br /> <br />Because of the strong tendency of Pacific salmon to return <br />to their natal stream to spawn, different populations may <br />follow essentially independent evolutionary pathways. To <br />the extent that directional forces (natural selection) and <br />random factors (founder effect and genetic drift) have <br />individually shaped the genetic makeup of these popula- <br /> <br />Robin S. Waples and Gary A. Winans are geneticists with <br />the Coastal Zone and Estuarine Studies (CZES) Division, North- <br />west Fisheries Center, National Marine Fisheries Service, 2725 <br />Montlake Boulevard East, Seattle, WA 98112. Fred M. Utter <br />recently retired as head of the genetics program for CZES. Conrad <br />Mahnken is head of the Fisheries Enhancement Task in CZES. <br /> <br />September - October 1990 <br /> <br />tions, each repre~ents a potentially separate stock (Ricker <br />1972). Given the ~xtensiv~ geographic range of some of the <br />species (e.g:, chiIitook salmon [0. tshawytsclza] spawn from <br />central Califbrnia!to the USSR, and as far inland as eastern <br />Idaho and the Caradian Yukon), the number of stocks that <br />might meriUndividual management consideration is daunt- <br />ing. <br /> <br />Oceanic Harvest <br /> <br />The above pict~re is enormously complicated by the fact <br />that almost all hilirvests of Pacific salmon occur away from <br />the spawning grqunds. Because the massive physiological <br />changes salmon tindergo in the spawning migration greatly <br />reduce market v41ue of the flesh, most fisheries occur at <br />sea or near the Imouth of major river systems. In such <br />fisheries, targeti'ig specific stocks is generally impossible; <br />some oceanic fis~eries, such as the troll fishery off the <br />Washington coasit, harvest fish spawned as far away as <br />California and AI~ska (Utter et a1. 1987). <br />The mixed-stoqk nature of most Pacific salmon fisheries <br />has two important consequences for management purposes. <br />First, effective regulation of individual stocks is difficult. <br />For example, it is loften not possible to restrict catches from <br />endangered or depleted stocks without limiting the entire <br />fishery. Second, because anadromous fish are considered <br />to be a resource ~f the state or country in whose waters <br />they were spa wIled, fishing rights cannot be determined <br />simply on the ba~is of geographical location of the fishery. <br />The questions, "~ho is catching whose fish?" and "What <br />compensation is d~e as a result?" are of considerable interest, <br />but answers satisf~ctory to all parties are difficult to achieve. <br /> <br />14rtificial Propagation <br /> <br />Increased fishirjg pressure, destruction of spawning hab- <br />itat, and blockage lof migratory routes by hydroelectric dams <br />have all contribqted to the reduction in abundance of <br /> <br />@ Copyright 1990 by the American Fisheries ?ociety. <br /> <br />19 <br />
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