Wildlife

Alaska salmon getting smaller

Alaska salmon have gotten smaller in recent decades, a downsizing that appears to be largely driven by climate change and increased competition for food as hatcheries release some 5 billion young fish into the North Pacific each year, according to a study published this month by U.S. and Canadian researchers in the science journal Nature Communications.

Alaska provides the vast majority of the United States’ wild salmon, and their smaller size is reducing the number of eggs that these fish produce and their value to commercial and other fishermen.

That decline encompasses salmon runs all over the state but varies by species and region. Chinook returning across a broad expanse of western and northern Alaska were some 10% smaller than the average size before 1990. Meanwhile in southeast Alaska, sockeye salmon declined — on average — by only about 2%.

Many of these salmon appear to be returning from the ocean earlier to freshwater spawning grounds, and that’s why they are smaller as they reach coastal-area harvest zones.

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