A new study has found four species reduced in size, with climate change and competition from hatchery-raised cousins as possible factors
Alaska’s salmon appear to be getting smaller.
The fishermen and women knew something was off with their catch. “At first, it was just a general comment by everybody: ‘The fish, yeah, I didn’t get any big ones this year,’” said Richard Burnham, who has commercially harvested salmon for four decades in the interior Alaska village of Kaltag.
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Now, a new study has borne out those observations on a huge scale, documenting body size declines in fish across the entire state of Alaska in four different species of salmon: chinook, sockeye, silver and chum.
Alaska is “the last largely pristine North American salmon-producing region”, the authors write. Yet the size of the Yukon region chinooks – the largest of the four salmon species – has diminished the most, by 10% compared with those caught before 1990.
The bodies of commercially valuable sockeye shrank by 2% statewide, and silver salmon grew 3% physically smaller.
One likely factor, the authors say, is climate crisis-driven changes in the quality or availability of the fishes’ food. A second constant, albeit weak, dynamic was that all four species were smaller when they were competing with larger numbers of a fifth species of Alaska salmon, the hatchery-raised pink.
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