A University of Washington study that was published in the journal Fish and Fisheries says that Chinook salmon are getting smaller in size in Alaska and throughout the West Coast. Or at least the big ones are becoming less frequent to find.
The largest and oldest Chinook salmon — fish also known as “kings” and prized for their exceptional size — have mostly disappeared along the West Coast.
That’s the main finding of a new University of Washington-led study published Feb. 27 in the journal Fish and Fisheries. The researchers analyzed nearly 40 years of data from hatchery and wild Chinook populations from California to Alaska, looking broadly at patterns that emerged over the course of four decades and across thousands of miles of coastline. In general, Chinook salmon populations from Alaska showed the biggest reductions in age and size, with Washington salmon a close second.
“Chinook are known for being the largest Pacific salmon and they are highly valued because they are so large,” said lead author Jan Ohlberger, a research scientist in the UW’s School of Aquatic and Fishery Sciences. “The largest fish are disappearing, and that affects subsistence and recreational fisheries that target these individuals.”
Chinook salmon are born in freshwater rivers and streams, then migrate to the ocean where they spend most of their lives feeding and growing to their spectacular body size. Each population’s lifestyle in the ocean varies, mainly depending on where they can find food. California Chinook salmon tend to stay in the marine waters off the coast, while Oregon and Washington fish often migrate thousands of miles northward along the west coast to the Gulf of Alaska where they feed. Western Alaska populations tend to travel to the Bering Sea.
After one to five years in the ocean, the fish return to their home streams, where they spawn and then die.
Despite these differences in life history, most populations analyzed saw a clear reduction in the average size of the returning fish over the last four decades — up to 10 percent shorter in length, in the most extreme cases.