The striking correspondence between changes in Chinook salmon abundance and mortality of northern and southern resident killer whales suggests that prey limitation was an important factor in recent population declines. As killer whales are apex predators, predation can be disregarded as a potential source of mortality, and anthropogenic threats to these populations that have been identified to date (Fisheries & Oceans Canada 2008) cannot explain the sudden and widespread increase in mortality rates that occurred concurrently in the two populations during the late 1990s. We hypothesize that these killer whale populations are dependent on Chinook salmon as their primary year-round food resource, and that alternative prey resources were insufficient to avert nutritional stress during years when availability of Chinook suddenly and sharply declined. rsbl.royalsocietypublishing.org/content/early/2009/09/14/rsbl.2009.0468.full
Posted on: Sun, 10 Aug 2014 04:33:42 +0000
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