Abstract.— Geographic variation in 

 minisatellite DNA was examined in 42 

 stocks of chum salmon, Oncorhynchus 

 keta, from the eastern and western 

 Pacific by restricting genomic DNA 

 with Haelll and hybridizing it with two 

 minisatellite probes. Regional differen- 

 tiation in allelic frequencies at the two 

 minisatellite loci was observed; Japa- 

 nese stocks were distinct from Russian 

 and Yukon River stocks, and stocks 

 from those two regions were distinct 

 from stocks in southeast Alaska and 

 British Columbia. No significant an- 

 nual variation was observed in allelic 

 frequencies at the two loci for three 

 stocks. Simulated mixed fishery samples 

 of 100 Japanese chum salmon were re- 

 solved with a baseline of nine Japanese 

 stocks with an average error of 0.59c per 

 mixture stock. Similarly, simulated 

 mixtures of Yukon River chum salmon 

 resolved with a baseline of five stocks 

 resulted in an average error of 0.6% per 

 mixture stock. Fraser River chum 

 salmon mixtures were resolved with an 

 average error of 3% per mixture stock. 

 With Asian and North American stocks 

 pooled into two groups, accuracy of clas- 

 sification for individual fish to conti- 

 nent of origin was 78% for 323 Asian 

 fish, and 94% for 797 North American 

 fish. Minisatellite DNA variation can 

 be successfully applied to problems of 

 stock discrimination in chum salmon. 



The use of minisatellite DNA variation 

 for stock identification of chum 

 salmon, Oncorhynchus keta 



Terry D. Beacham 



Pacific Biological Station, Department of Fisheries and Oceans 



3 1 90 Hammond Bay Road 



Nanaimo, British Columbia. Canada V9R 5K6 



e-mail address Beachamt@pbs dfo.ca 



Manuscript accepted 19 April 1996. 

 Fishery Bulletin 94:611-627 (1996). 



Chum salmon, Oncorhynchus keta, 

 have the widest natural geographic 

 distribution of all Pacific salmon 

 species, ranging in Asia from Korea 

 to the Arctic coast of Russia, and in 

 North America from California to 

 the Arctic coast of Canada (Salo, 

 1991 ). Chum salmon support major 

 fisheries in both Asia and North 

 America, and management of the 

 fisheries in North America usually 

 requires that stock composition of 

 the catches be determined in order 

 to prevent excessive exploitation of 

 particular stocks. A variety of meth- 

 ods have been applied to discrimi- 

 nate among chum salmon popula- 

 tions and to estimate stock compo- 

 sition in fisheries. Early work con- 

 sisted in applying physical tags to 

 individual fish (Pritchard, 1931; 

 Anderson and Beacham, 1983), but 

 quantitative estimates of stock com- 

 position were generally unable to be 

 derived from these studies. Varia- 

 tion in scale characters has also 

 been used for stock identification in 

 chum salmon (Kovtun, 1983; Niko- 

 layeva and Semenets, 1983; Ishida 

 et al., 1989), but the ability to dis- 

 criminate among stocks in a local- 

 ized area is limited. 



Genetic methods of stock identi- 

 fication for chum salmon have been 

 evaluated by using both protein- 

 and DNA-level variation. Stock 

 identification techniques based 

 upon genetic variation at protein- 

 coding loci have been shown to pro- 

 vide information on stock structure 



(Okazaki, 1982; Omelchenko et al., 

 1992; Kondzela et al., 1994; Phelps 

 et al., 1994; Winans et al., 1994) and 

 stock composition in chum salmon 

 fisheries (Beacham et al., 1985, 

 1987). By screening genetic varia- 

 tion at the DNA level, using mito- 

 chondrial DNA variation (Ginatu- 

 lina and Mashkin, 1990; Gina- 

 tulina, 1992; Cronin et al., 1993; 

 Park et al., 1993) and minisatellite 

 DNA variation (Taylor et al., 1994), 

 the population structure of a spe- 

 cies can be determined. Variation in 

 minisatellite DNA has been used to 

 provide accurate and precise esti- 

 mates of stock composition in simu- 

 lated mixtures in a number of 

 Oncorhynchus species (Beacham et 

 al., 1995, 1996; Miller et al., 1996. 

 Minisatellite DNA consists of tan- 

 demly repeated arrays of nucle- 

 otides where each array contains a 

 core sequence (Jarman and Wells, 

 1989). Variable numbers of the tan- 

 dem repeats ( VNTR) occur between 

 restriction sites, resulting in allelic 

 variation at the minisatellite locus. 

 Heterozygosity at these loci can be 

 substantially greater than that 

 commonly observed with protein 

 electrophoresis. Average heterozy- 

 gosity at protein electrophoretic loci 

 is less than 10% in chum salmon 

 (Winans et al., 1994); heterozygosi- 

 ties at minisatellite loci in salmo- 

 nids are reported to be between 35 

 and 80% (Taggart and Ferguson, 

 1990; Bentzen and Wright, 1993; 

 Taylor et al., 1996). The high level 



