DAPHNIA BY JOHN BERRY

The Norfork tailwater has been fishing poorly lately. When I check with other guides and anglers, I have been getting the same story. They see plenty of fish but the bite is slow, very slow. One of the bait guides that I talked to said that, when he cleaned the few trout that his clients had caught, they were full of tiny (the size of a pin head) translucent organisms that looked like insect eggs to him. I checked with everybody I could find on stream and several had made the same observation. We all agreed that it was Daphnia.

I had run into this situation a few years ago, when I was guiding a corporate group for River Ridge Inn on the Norfork River. None of the guides were catching many fish. When one of the guides pumped their trout’s stomach, he found they were all gorged on the tiny translucent organism that another guide (biology major) identified as Daphnia. They are commonly referred to as water fleas.

What is Daphnia? I was an accounting major, so I didn’t have a clue. Luckily for me I live next door to Dr. Eddy Dry an entomologist and a biology professor at Arkansas State University Mountain Home. I was out cutting my grass the other day and saw him outside mulching his garden. I stopped for a break and went over to see what he knew about Daphnia.

It turned out that he knew quite a lot. He began by telling me that he was no expert on the subject. He went on to say that Daphnia was a micro crustacean like scuds although much smaller. They are classified as zooplankton, which are small aquatic animals that are at the mercy of the currents. As a result, they can be washed through the generators from the lake into the river.

Though at the mercy of currents, they can migrate vertically (up and down) for food, sunlight or to escape predators (they are pretty near the bottom of the food chain). They are frequently used as fish food in aquariums. Eddy was not sure what had caused the bloom or increase in the Daphnia but assumed it was due to the high lake levels and mild winter that we had. This is a natural phenomenon.

We don’t know how long it will last and we definitely don’t know how to control it. We do know that trout on the Norfork tailwater are keying in on it and gorging on it. The best bet is to employ a strategy of tempting the trout with larger bites that are easily seen. Several guides on the river are using brightly colored San Juan worm and egg combinations with limited success. You could also try streamers like woolly buggers and marabou jigs.

This won’t go on forever. Until then try something bigger and brighter to bring them in.

John Berry is a fly fishing guide with Blue Ribbon Guides in Cotter, Arkansas and has fished our local streams for over thirty years.