Coexisting with Orcas

Coexisting with Orcas

Southern resident orcas in the Salish Sea are facing population decline at the hands of a severe drop in salmon numbers. Noise pollution from ship traffic, the pollution of the ecosystem and bioaccumulation of toxics in southern resident orcas are other massive stressors on the population.

Bioaccumulation occurs when toxics enter the food chain and predators begin to consume contaminated prey. As orcas consume more and more contaminated salmon, they also consume the toxics in the fish, accumulating dangerously high levels of pollution in their fat reserves. Like all marine mammals, orcas rely on the energy in their fat for when prey is scarce. This is an all-too common occurrence for southern residents. Chinook salmon, their primary prey, have collapsed across the west coast, leaving fewer fish for the whales.

Orcas are icons in the Salish Sea region, but even here, there are plenty of people that don’t know that southern residents are different from the transient, mammal-eating orcas that visit the Salish Sea. Even fewer people outside of the region know about these ecologically unique whales. Though they are called “residents” because they live in the Salish Sea for more than half the year, these whales migrate every winter to the open waters of the Pacific, feeding on chinook salmon returning to the major rivers on the west coast. These orcas have been seen as far south as Monterey Bay, but many Californians, Oregonians and Washingtonians don’t know that these endangered orcas rely on salmon runs along the Pacific Coast.