The fly-fishing website Midcurrent.com recently posted an excerpt from a 2009 book called “The New Scientific Angling: Trout and Ultraviolet Vision” by one Reed Curry.
The excerpt doesn’t get into the whole ultraviolet vision thing, so I’m still in the dark on that, so to speak.
But Curry does pose a valid question that has also occurred to me many times, as I’m sure it has to many others. Noting that trout have perfectly good eyesight, he shows a picture of a Quill Gordon dry fly, and asks: “How is it then that a large brown trout will see this …”
Then he shows a picture of the real mayfly the Quill Gordon is supposed to imitate, and finishes his thought: “… and accept it as this?”
It’s true: even the most handsome and well-made dry fly looks about as much like a real mayfly as a scarecrow looks like a human being. And yet vast numbers of trout have made the mistake of trying to eat them, and will continue to do so.
Curry’s point is that trout eat dry flies because they agree with an image stored in the fish’s instinctive database. In other words, the dry fly possesses what other thought leaders on the subject refer to as triggers.
He also notes that the fish’s database query may have been answered with a “maybe” instead of a “yes,” which can be just as good, since it may inspire further investigation with other senses. “In order for the fish to touch and taste, he takes an object in his mouth, hands being in short supply,” Curry writes.
Bob Wyatt, whose recent book “What Trout Want: The Educated Trout and Other Myths” is the best fishing book of the year and possibly the decade, described studies showing predators like birds and fish employ a “search image” to efficiently distinguish food from the random bits of junk lying on the ground or floating in a stream.
Wyatt has simplified his own fly selection to just a few patterns with the basic triggers, usually nothing more than hare’s ear fur body and a small tuft of deer hair for a wing, and uses them to catch huge trout in gin-clear rivers in his adopted homeland, New Zealand.
We live in a golden age of experimentation in fly-tying. We probably had all the fly patterns we needed before the start of World War II, but we’ve continued to invent new ones anyway. New patterns, meant to solve this problem or that and catch us all more trout, sell more flies, and hooks and hackle feathers, and books and magazines.
To be sure, people who invent new patterns are serious students of nature, not cynical frauds trying to sell us stuff we don’t need. They genuinely have new ideas. And inventing new flies is fun.
Today, everyone’s a videographer with their own TV show, i.e. YouTube channel, and many of us just can’t resist dreaming up new flies to show to the rest of us. Look how many videos you can find about tying the Intruder. Many of them are two-parters. It’s the era of the 20-minute tie.
And yet look at the things that have caught trout beyond count for generations — and I don’t even mean flies: the Acme Phoebe. the Mepps Spinner. the Panther Martin. the Dardevle spoon.
No trout with any eyesight at all would ever confuse any of them with a real minnow — but they try to eat them.
These lures, and the Intruders, and Bob Wyatt’s simple bugs, and the elegant Quill Gordon, possess the triggers that make trout bite. They match some kind of built-in search image. They create an impression that corresponds with info in the database.
As unscientific as it may sound, I’m starting to think the best approach is to fish with the flies you like best and be confident the fish will like them, too, as long as you make them seem alive on or in the water.
Morgan Lyle’s commentary appears regularly in The Daily Gazette. Reach him at firstname.lastname@example.org.