Variation in Body Size, Morphology, Egg Size, and Biochemical Genetics of Pink Salmon in British Columbia

Abstract

Stocks of pink salmon Oncorhynchus gorbuscha in British Columbia that were spawning from August through October 1982–1985 in rivers of different size were surveyed for variation in size, morphology, egg weight, and biochemical genetics. Fish that spawned in large rivers were longer and had proportionately larger heads, thicker caudal peduncles, and larger fins than those that spawned in small rivers. Differences in gill raker counts between the broodlines (i.e., fish spawned in even-numbered years versus those spawned in odd-numbered years) were greater than among stocks within broodlines. Differences in morphometric characters were greater among stocks within broodlines than between broodlines; this indicated morphometric adaptation to local conditions in the natal river. As the spawning season progressed, mean lengths of males and females and weight of eggs increased. Electrophoretic analysis indicated that in the odd-year broodline, pink salmon could be generally distinguished as originating from five regions; Skeena River, north and central coast (combined), south coast, Fraser River, and Puget Sound. In the even-year broodline, pink salmon could be distinguished from three regions: Queen Charlotte Islands, north and central coast (combined), and south coast. Variation in allelic frequencies between the broodlines was greater than among stocks within each broodline. Within stocks, allelic frequencies were generally stable over a 2-year period.