Something was killing baby salmon. Scientists traced it to a food-web mystery

Los Angeles Times

The biologists working in a fish hatchery near Shasta Dam grew increasingly concerned last year when newly hatched salmon fry began to act strangely — swimming around and around, in tight, corkscrewing motions, before spiraling to their deaths at the bottom of the tanks.

Certain runs of chinook salmon in California are imperiled; the hatcheries and the fry raised there are the federal government’s last-ditch effort to sustain these ecologically and economically vital fish populations.

So, when scientists observed the young salmon’s screwball behavior, they reached out to their networks in oceanography, ecology and fisheries: Had anyone seen anything similar? Did anybody know what was going on?

As it happened, scientists and hatchery managers around the Great Lakes had observed similar abnormalities in lake trout, beginning in the 1960s. Although it took a few decades, scientists eventually unlocked part of the mystery: The fish had a deficiency of thiamine, or vitamin B1.

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