ramblings of a catskill fly fisher

Is there an evolution in trout feeding behavior?

By TONY BONAVIST
Posted 3/8/23

When I begin tying flies, the folks who mentored me followed the Catskill School. By that, I mean that they subscribed to the techniques used by the Darbees and Dettes, by Rube Cross and Art Flick, …

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ramblings of a catskill fly fisher

Is there an evolution in trout feeding behavior?

Posted

When I begin tying flies, the folks who mentored me followed the Catskill School. By that, I mean that they subscribed to the techniques used by the Darbees and Dettes, by Rube Cross and Art Flick, and fathered by Theodore Gordon.

In those days, most dry flies were tied using wood-duck flank feathers for wings. I tied my flies that way for over 40 years, and those imitations rose a lot of trout for me.

Then at some point, I decided to tie those traditional Catskill patterns without wings. In so doing, I saved a time-consuming step and the cost of wood duck flank feathers, and learned that wings were not necessary.

I found that most fly tiers who used wood duck flank feathers for wings  separated the wings, so in essence there were two wings. In contrast, my observations of newly hatched mayflies revealed that those insects held their wings together while floating along. That in itself was a major anomaly I found with traditional Catskill flies when compared to natural insects.

As I evolved as a fly tier and angler, I found that feeding trout began to ignore my wingless flies. Was it my pattern, or another reason that my offerings were allowed to float along untouched? That’s when I realized that many of the trout I was casting to—especially if they were of wild stock—were not taking duns off the surface. Instead, and despite what appeared to be rise forms, there were surface disturbances made by trout taking hatching mayflies at or just below the surface.

When trout are feeding in this manner, it is very easy for anglers to be deceived into believing that trout are taking duns when they are not. I know that I was.

That is one of the little traps that we can easily fall into as fly fishers. We see hatching flies and surface activity, and all too frequently assume that the fish are taking duns. Hatching flies, along with visible surface activity, always equals rising trout; right? Unfortunately, that is not always the case.

There was a time, not so long ago, when anglers with a good selection of Catskill-style dry flies could go afield and expect some excellent sport. Assuming, of course, they found a decent hatch of mayflies. From what I witnessed over the last 20 years or so, that is no longer true. From what I have seen, there has been a change in the way trout feed during mayfly hatches.

These days, wild trout no longer take hatching duns with the abandon they once did. Instead, it seems that wild fish in particular are taking mayfly nymphs in the surface film or on the way to the surface. I’ve watched this kind of feeding during some large hatches—hundreds of duns on the water, with few if any taken.

Once I learned that hatching flies did not always mean trout were taking flies off the surface, I tried a number of techniques to try and rise trout when they were feeding this way. I used nymphs fished a few inches under the surface with a small strike indicator, swung small wet flies in front of feeding fish, and dead drifted a nymph just under the surface. Although I hooked a trout on occasion, there was no consistency.

Then a few years ago, I had a thought. Since most trout appeared to feed on hatching mayflies at or just below the surface, how about floating a small fly in the surface film? There were some small olive mayflies around at that time, so I tied up a few size 18 parachute pheasant tail nymphs.

A few days later, a friend and I found a pretty good olive hatch, with trout leaving the duns for the hatching flies. These were mostly small browns, but still worthy opponents. During that hatch, I’m happy to say that I was finally able to hook a few trout, fishing my little parachute pheasant tail nymph, across and downstream.

While I cannot say I solved the problem, it was a huge step forward, a technique I will try to improve in the future.

The question now remains: what caused wild trout to change from surface feeders to sub-surface feeders? Is it due in part to fishing pressure? Or because there are more avian predators, such as eagles and ospreys, around, since the use of DDT was banned? Are trout aware of those threats, and have they adjusted their feeding accordingly? Is this change in feeding a learned behavior or a conditioned response to external pressure?

I spoke to a good friend about my observations, and this is in part what he said. “The season for cutthroat trout on Flat Creek, in the National Elk Refuge, near Jackson, WY, opens to fishing on August 1. At the beginning of the season, those cutthroats are easy to catch. But by the end of the season, two months later, they become very wary and very difficult to catch.”

This behavior appears to be a response to fishing pressure. Yet it demonstrates the ability of those cutthroats to adapt, in order to avoid getting caught.

So it seems that our wild trout friends have the ability to change the way they feed and behave as a protective and as a survival mechanism. I don’t have answers to the issues I’ve raised here, other than to say that wild trout are becoming harder and harder to catch.

Catskill School, fly fishing, dry flies

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