Who's Eating Who?


It’s been a dramatic summer for both fish-eating Orcas and salmon in Northwest waters. Our resident Orca whales, some appearing undernourished, up and left their normal foraging among the San Juan Islands. Their preferred diet of wild Chinook (King) salmon had decreased and it was assumed they went elsewhere to feed.


Meanwhile our local market kept selling us lovely wild salmon from Alaska and like many Northwesters it’s in our weekly diet. Even though I know all too well that overfishing is a global issue, like other humans, I often choose to serve my own immediate hungers, ignoring long term costs. Also, in this case, I’ve been relying on the many U. S. regulations on salmon fishing to keep the salmon populations sustainable.

Not Enough Salmon

Efforts to help the Orcas get food include a proposal to ban motor vessels from their feeding areas.  While this is being considered, San Juan County officials gleaned more ideas from public comments. Some would directly increase Pacific wild salmon by increasing hatcheries or banning human fishing. Other ideas were pretty common sense bolstering of current regulations. A last group would increase the wild salmon’s forage fish by shoring up habitats and stop the introduction of  invasive species like Atlantic salmon that compete for the wild salmon’s diet.

Nature Acts Quickly

While such ideas worked their slow way through human committees, - whoosh – a broken pen net in a local fish farm loosed up to 300,000 Atlantic salmon into local waters. Now the word went out fast to fisher folk everywhere to catch them - no limits on where or how many - just help clean up this potential mess.

It’s still unknown if the potential threats of the Atlantic farmed salmon occurred: possible viruses, interbreeding with wild salmon, eating up the forage fish of wild salmon.  In addition to the call to catch them, state officials quickly stopped permitting other fish farms in the state and the whole controversy around their impact on the environment, fishy feedlots that they are, was up for new debate.

Local whale watchers wondered if the resident Orcas might return and shift their eating to these farmed salmon, but the escaped salmon dispersed over a 10 day period. Then on September 4th, back come the resident Orcas, all three pods to the delight of whale watching humans, seemingly healthy with only some concern about the body size of some of the juveniles.

Competing Food Webs

Which all leaves me paying more attention to the larger food webs for the Orcas, and who competes for the choicest bits. The bears will probably not change their diets, but I’m paying more attention to the kind of salmon that I’ve been eating.

The Orcas prefer Chinook salmon, as do most humans, but there are four other types of salmon (Coho, Chum, Sockeye, and Pink) pretty much in decreasing levels of the omega-3 fats that make them calorie dense.                  

I’ll be watching our supermarket options more closely and digging into Monterey Aquarium’s Fish guide. As in many ecological choices, the details can quickly get complex. In this case, I’m studying which of five types of salmon are raised wild and farmed and caught where and by what means.

More on the state of salmon eating in future posts. Meanwhile the Orcas are back and all the whale watching humans are delighted, out on the water with their cameras (and smart phones) clicking away.