MEPS 449:245-262 (2012)  -  doi:10.3354/meps09528

Annual coastal migration of juvenile Chinook salmon: static stock-specific patterns in a highly dynamic ocean

S. Tucker1,*, M. Trudel1,2, D. W. Welch1,3, J. R. Candy1, J. F. T. Morris1, M. E. Thiess1, C. Wallace1, T. D. Beacham1

1Pacific Biological Station, Fisheries and Oceans Canada, 3190 Hammond Bay Rd, Nanaimo, British Columbia V9T 6N7, Canada
2Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
3Present address: Kintama Research Services Ltd, 10-1850 Northfield Road, Nanaimo, British Columbia V9S 3B3, Canada

ABSTRACT: While recent studies have evaluated the stock-specific coastal migration of juvenile Chinook salmon, it remains unclear if these seasonal patterns are consistent between years, particularly when ocean conditions change dramatically. Here we contrast the abundance, distribution and seasonal stock compositions of juvenile Chinook salmon between years in 3 oceanographic regions of the Pacific from southern British Columbia to southeast Alaska. Between 1998 and 2008, we surveyed salmon in various months from June through March, in different regions along the shelf. Variable conditions in the North Pacific Ocean, as well as large overall shifts in ocean regimes were extensively documented over this decade. We employed genetic stock identification to identify mixed-stock compositions; fish (n = 6274) were allocated to one of 15 regional and 40 sub-regional stocks. Catch-per-unit-effort and distribution of salmon, as denoted by centre of mass, varied significantly between seasons, regions and years. In a similar manner, fish body size and dry-weight varied significantly between years, seasons and regions. Despite these inter-annual differences in catch, distribution, fish growth performance and large variations in ocean conditions encountered by salmon over the time period of the study, we observed no response in terms of shifts in stock-specific distributions. Regional stock composition was similar between years, suggesting migration patterns for all stocks remain consistent despite fluctuations in the marine environment: local stocks remain resident in respective coastal areas during their first year at sea, except for Columbia River salmon, which move quickly into waters north of Vancouver Island in summer.


KEY WORDS: Juvenile Chinook salmon · Ocean migration · DNA stock identification · Variable ocean conditions


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Cite this article as: Tucker S, Trudel M, Welch DW, Candy JR and others (2012) Annual coastal migration of juvenile Chinook salmon: static stock-specific patterns in a highly dynamic ocean. Mar Ecol Prog Ser 449:245-262

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