June is Orca Action Month and conservation organizations across the region have been helping to raise awareness about the challenges facing our southern resident orcas. The challenges are many, but one of the biggest is the decline in Chinook salmon, the orcas’ primary food source.
Why are orcas so reliant on this particular type of salmon? Chinook are the largest of the Pacific salmon species. Like all salmon, they are born in freshwater rivers and streams, then migrate out to the ocean to live their adult lives before returning to freshwater to spawn. They have one of the largest ranges of any salmon and grow much larger than other types of salmon, such as coho, chum and sockeye.
Their size is the main reason southern resident orcas are so dependent upon Chinook salmon for survival. As you can see by the graph below, Chinook provide much more energy per fish than other salmon species.
Say you’re an orca and you’re deciding what kind of salmon to eat: you’re likely going to target a fish that gives you the most “bang for your buck”—or energy for your effort. Orcas rely on building up fat stores when there’s an abundance of food, and successfully hunting for Chinook allows them to get the most calories per fish. That’s why Chinook make up 80% of a southern resident’s diet.
We’ve created a fun, interactive infographic that shows the importance of Chinook salmon to the southern resident population. Check it out to learn more about their population levels over time and why orcas depend on this important local species for survival.
Join us for our Orca Awareness Celebration!
Don’t forget: sign our petition in support of orcas!
We can all do our part to help the southern resident orcas. Take a moment to sign our petition asking Congress to fully fund programs in support of orca recovery. Multiple federal programs of vital importance have been eliminated in the Trump Administration’s proposed fiscal year 2020 budget. Join the Seattle Aquarium in making our voices heard!