Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1.
Environmental correlates of life-history variation in juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum)
Article first published online: 24 JAN 2006
Journal of Fish Biology
Volume 37, Issue 1, pages 1–17, July 1990
How to Cite
Taylor, E. B. (1990), Environmental correlates of life-history variation in juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum). Journal of Fish Biology, 37: 1–17. doi: 10.1111/j.1095-8649.1990.tb05922.x
- Issue published online: 24 JAN 2006
- Article first published online: 24 JAN 2006
- (Received 11 October 1989, Accepted 19 January 1990)
- Oncorhynchus tshawytscha;
- life history variation;
- environmental influence
Throughout its native North Pacific, the chinook salmon, Oncorhynchus tshawytscha (Walbaum), exists as twolife-history types that aredistinguished by the age at which juvenile salmon migrate to sea as smolts. ‘Stream-type’ chinook migrate seaward after I or more years of feeding in fresh water, whereas ‘ocean-type’ fish migrate to sea as newly emerged fry or after 2–3 months in fresh water. Stream-type chinook predominate in populations distant from the sea south of 56° N, and in both inland and coastal populations north of this point. By contrast, ocean-type chinook predominate in coastal populations south of 56° N, but are rare in populations in more northerly latitudes. Stream-type populations are associated with areas of low ‘growth opportunity’ (as measured by temperature and photoperiod regimes) and/or areas distant from the sea compared to ocean-type. Geographic variability in juvenile life history is suggested to result, in part, from environmental modulation of smolting timing via differences in growth opportunity among geo-graphic areas. In addition, differences in migration distance and temperature regime may result in selection for different sizes at migration among populations which, through differences in growth opportunity, might promote geographic variability in age at seaward migration.