The connection seems obvious until you look into the complexities:
- Puget Sound chinook salmon are listed as a “threatened” species.
- Southern Resident killer whales, which frequent Puget Sound, are listed as “endangered.”
- Southern Resident killer whales eat primarily chinook salmon.
Therefore … isn’t it obvious that the shortage of Puget Sound chinook has had a major impact on the whales?
Once you begin to challenge the assumptions — as a seven-member scientific panel has done — a more complex picture emerges. It is not easy to sort out predator-prey interactions, especially considering that the prey may include hundreds of individual salmon stocks, some of which are doing quite well.
The independent panel (PDF 144 kb), made up of U.S. and Canadian scientists, tackled the question of whether cutbacks or elimination of salmon fishing could help rebuild the killer whale population at a faster rate. The panel’s preliminary conclusion is that reducing fisheries could have a slight benefit, but only if certain assumptions hold true.