574 



Fishery Bulletin 94(3). 1996 



a high degree of genetic differentiation between 

 samples from different geographic regions (22.3%). 

 However, the level of differentiation between samples 

 within regions was actually less than the level of tem- 

 poral variation. This could be due to the extensive 

 number of stock transfers within regions that have 

 taken place for coho salmon. Therefore, we concluded 

 that although the transferrin locus may be used to 

 discriminate between samples from different geo- 

 graphic regions, caution must be used when attempt- 

 ing to use this locus to discriminate between samples 

 from within a region. 



It is important to realize that these results and 

 conclusions are based on data from only one locus. 

 Accurate GSI procedures rely upon baseline data 

 from many polymorphic loci. Our current protocol for 

 obtaining baseline genetic data includes using more 

 than 60 loci that have been shown to be polymorphic 

 for coho salmon. A large baseline of genetic informa- 

 tion, from potential source populations and from 

 enough loci with significant allele-frequency differ- 

 ences between stocks, to identify the contributing 

 stocks is generally required for GSI methods to be 

 successful (Milner et al., 1985). 



Our results provide further evidence that identifi- 

 able regional genetic differences can be detected 

 among coho salmon populations. GSI investigations 

 of coho salmon will be more precise when data from 

 the transferrin locus is used in conjunction with 

 allozyme data and perhaps DNA-type variation (Park 

 et al., 1993). As these data show, the transferrin lo- 

 cus exhibits significant allele-frequency differences 

 between stocks from different geographical areas and 

 has the potential to increase the discriminating 

 power of GSI analyses for coho salmon. 



Acknowledgments 



The authors are grateful to David Kuligowski and 

 Eugene Tezak for assistance with laboratory work. 

 Kathleen Neely helped create the map of sample lo- 

 cations. David Teel and Jeff Hard provided valuable 

 reviews of previous versions of this manuscript. 



Literature cited 



Aebersold, P. B., G. A. Winans, D. J. Teel, G. B., Milner, 

 and F. M. Utter. 



1987. Manual for starch gel electrophoresis: a method for 

 the detection of genetic variation. U.S. Dep. Comnier, 

 NOAATech. Rep. NMFS 61. 

 Bartley, D. M. 



1987. The genetic structure of chinook and coho salmon 

 populations in California, with a note on the genetic vari- 



ability in sturgeon (Acipenseridae). Ph.D. diss., Univ. 

 Calif., Davis, CA, 204 p. 

 Bartley, D. M., B. Bentley, P. G. Olin, and G. A. E. Gall. 



1992. Population genetic structure of Coho salmon 

 (Oncorhynchus kisutch) in California. Calif. Fish Game 

 78:88-104. 



Brown, L. R., P. B. Moyle, and R. M. Yoshiyama. 



1994. Historical decline and current status of coho salmon 

 in California. N. Am. J. Fish. Manage. 14:237-261. 

 Chakraborty, R. 



1980. Gene-diversity analysis in nested subdivided 

 populations. Genetics 96:721-726. 

 Grewe, P. M., C. C. Krueger, C. F. Aquadro, and B. May. 

 1994. Stability of allozyme and mitochondrial DNA markers 

 among three year-classes of lake trout propagated from Sen- 

 eca Lake, New York. N. Am. J. Fish. Manage. 14:467^174. 

 Hjort, R. D., and C. B. Schreck. 



1982. Phenotypic differences among stocks of hatchery and 

 wild coho salmon, Oncorhynchus kisutch, in Oregon, Wash- 

 ington, and California. Fish. Bull. 80:105-119. 

 May, B. 



1975. Electrophoretic variation in the genus Oncorhynchus: 

 the methodology, genetic basis, and practical application 

 to fisheries research and management. M.S. thesis. Univ. 

 Washington, Seattle, 95 p. 

 Melntyre, J. D., and A. K. Johnson. 



1977. Relative yield of two transferrin phenotypes in coho 

 salmon. Prog. Fish-Cult. 39:175-177. 



Milner, G. B., D. J. Teel, F. M. Utter, and G. A. Winans. 



1985. A genetic method of stock identification in mixed 



populations of Pacific salmon, Oncorhynchus spp. Mar. 



Fish. Rev. 47:1-8. 

 Milner, G. B. 



1993. Isozyme variation of coho salmon (Oncorhynchus 

 kisutch) and its potential to estimate stock compositions 

 of mixed-stock fisheries. Proceedings of the 1992 coho 

 workshop. May 26-28, 1992, Nanaimo, British Columbia, 

 p. 182-192. Canadian Dep. Fisheries and Oceans, Habi- 

 tat Management Sector, Policy and Information Unit, 327- 

 555 West Hastings St., Vancouver, B.C., V63 5G3, Canada. 



Nei, M. 



1978. Estimation of average heterozygosity and genetic 

 distance from a small number of individuals. Genetics 

 89:583-590. 



Olin, P. G. 



1984. Genetic variability in hatchery and wild populations 

 of coho salmon, Oncorhynchus kisutch, in Oregon. M.S. 

 thesis, Univ. California, Davis, CA, 77 p. 

 Park, L. K., M. A. Brainard, D. A. Dightman, and 

 G. A. Winans. 



1993. Low levels of intraspecific variation in the mitochon- 

 drial DNA of chum salmon (Oncorhynchus keta). Mol. 

 Mar. Biol. Biotech. 2:362-370. 



Pratschner, G. A. 



1978. The relative resistance of six transferrin phenotypes 

 of coho salmon (Oncorhynchus kisutch) to cytophagosis, 

 furunculosis, and vibriosis. M.S. thesis, Univ. Washing- 

 ton, Seattle, WA, 71 p. 



Rohlf, F. J. 



1994. NTSYS-pc. Numerical taxonomy and multivariant 

 analysis system, version 1.80. Exeter Software, Setauket, 

 New York", NY. 



Sandercock, F. K. 



1991. Life history of coho salmon (Oncorhynchus kisutch). 

 In ( ' Groot and L. Margolis (eds.), Pacific salmon life histo- 

 ries, p. 395—445. Univ. British Columbia Press, Vancouver, B.C. 



