Do Fish Sun Themselves in Winter?

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A piercing question -- Do fish actually sun themselves in winter?

In late winter, when the days are getting a little longer and the sun’s azimuth is higher, there starts to be a good deal more solar input into the river; as a result the fishing improves dramatically. The other day a friend and I went out to take advantage of a break in the weather. We wandered down to the Metolius for a few hours fishing on a beautiful sunshiny day.

We went to a place I know where a good pod of Bull Trout hang out. These fish have always had a tendency to move up and down the hole. Some days they’ll be high up in the run in the deeper water toward the head of the pool; other days they will be further back in the shallow water toward the tail. When we got to the river on this particular day they were as far back in the hole as I had ever seen them. They were stacked up in shallow water that could not have been more than a foot and a half deep. It suddenly seemed quite apparent to me they were there for a reason; they were enjoying the warmth of a little winter sunshine on their backs.

Seeing this unusual bit of fish behavior started me thinking. I began reflecting back over other times I had found fish in the shallows in the winter. I started to realize this sunning business may be a fairly common occurrence. I have run onto fish of all species rainbows, browns and bull gathered in the shallows at on time or another. I had thought they were there because of a lack of fishing pressure; now I’m not so sure. It seems pretty logical that fish, a cold blooded species, would move into shallow water where UV rays penetrate the best in order to gain warmth.

It’s logical enough I know, in the future when I am winter fishing, I will be looking pretty closely at sunny, shallow places in the river. I’m going to try real hard to validate my theory. I would be very interested if anybody else has thoughts or ideas on this subject.