I wonder why? Some rivers have Pinks every year.
Taken from McPhail (2007)
"Although the specific status of pink salmon is not a taxonomic issue, there are unsolved problems involving the relationships and distribution of the odd-year and even-year broodlines in this species. Because virtually all native populations of pink salmon mature at 2 years, the generations spawning on odd and even years are genetically isolated from one another and often differ in life-history characteristics (Heard 1991). Usually one brood line is dominant (i.e., there is a strong run one year followed by a much smaller run the next year). At the southern end of their North American distribution, including southern BC, odd-years runs are dominant, however, north of the Fraser River system, many rivers support relatively strong runs on both odd and even years. From Haida Gwaii, North to Alaska, even year runs are dominant. Presumably, both odd-year and even-year runs have evolved independently in different areas, but the reasons for the broad geographic pattern in run dominance is still a mystery. The pattern of mitochondrial variation in northern pink salmon suggests multiple Pleistocene divergences followed by a relatively recent (post-glacial) expansion from different sources, and perhaps different colonization routes for the odd-year and even year broodlines (Churikov and Gharrett 2002).
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Topic: is 2012 a larger pink run for the fraser? (Read 2762 times)