Researcher shows fishing has reduced salmon size in Alaska

After studying data going back to 1943, Kendall has discovered that the average length of a sockeye salmon is now 14 millimeters shorter than it used to be. She also discovered that the number of sockeye that spent two, instead of the normal three years, out at sea before coming upstream to lay their eggs, had increased by 16%, suggesting Mother Nature was trying to make up for losses incurred due to fishing.

Kendall, in her presentation to the International Marine Conservation Congress in Victoria, British Columbia, last month suggested that it’s not just fishing, or even over-fishing that is the problem; instead it’s the practice of going after the biggest fish that is really mucking things up. As she sees it, the largest salmon, generally pregnant females, who are caught in nets specifically designed to grab larger fish while letting the smaller ones pass through, wind up in the nets along with their egg carrying genes for a larger size, which are then lost when the fish is caught. The result is a disproportionate number of smaller fish representing each new generation, which of course leads to smaller and smaller fish as fishermen are forced to adjust down their net sizes.

via Researcher shows fishing has reduced salmon size in Alaska.

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