Photo of spawning chinook, one of the Alaska salmon getting smaller. Courtesy Ryan Hagerty, USFWS
Researchers found adult salmon in Alaska are smaller than they were before 1990. King salmon measured after 2010 were an average of eight percent shorter. Coho salmon measured 3.3 percent shorter, chum 2.4 percent, and sockeye 2.1 percent.
The decline in size means less value for commercial fishermen, less food for subsistence harvest, and fewer eggs left by spawning salmon. The researchers estimated the smaller king salmon resulted in 21 percent less value for the fishery and 26 percent less food for subsistence fishermen.
One likely cause, the study’s authors said, was climate-driven changes to the quality or availability of food for the salmon.