Snow cover good for brook trout, study finds

Snow is good for brook trout, and that could be bad news, according to a recent study sponsored by the Ellen's Creek's Watershed Group in Charlottetown.

The group hired Harriet Laver, an environmental biology major at UPEI, to look at how weather impacts the brook trout population. Laver used weather data from Environment Canada — including precipitation, temperatures and snow accumulations — and correlated it with the number of young-of-the-year trout (trout younger than one year) found by the watershed group every spring going back to 2014.

She found a clear connection.

"It turned out that the years that were colder during the winter, and had more snow accumulation as well, they seemed to result in young-of-the-year brook trout," said Laver.

In years of medium to high accumulation more than 100 trout had been captured. In years of low accumulation it was fewer than 75.

Laver thinks there could be a number of factors playing in the trout's favour with snow.

Snow on the ice would insulate the stream. Water temperatures below 4 C can kill eggs. Snow also provides shade, which brook trout prefer, and melting snow releases oxygen into the water, which would keep the fish healthier.

'It would lead to less insects'

There could be an indirect benefit as well.

"It helps with the insects too, which the brook trout rely on for food," said Laver.

"If the insects hatch too soon, if they hatch in the winter during a warm spell, it would lead to less insects in the spring and therefore less food for the brook trout."

Brook trout's need for snow could be bad news for the species on P.E.I., Laver concluded in her study, because climate change is expected to mean less snow on the Island.

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