There are secrets to be had in thin water.
By Ralph Scherder
THE ROUGHER THE ROAD GOT, the narrower the stream became, and by the time our convoy arrived at its destination, the flow was little more than a trickle. I’d decided to join a team of biologists from the Pennsylvania Fish & Boat Commission as they electroshocked the headwaters of one of my favorite streams. Although the mainstem had been designated Class A Wild Trout waters back in the early 1990s, its tributaries were never surveyed. I jumped at the chance to join, but I wasn’t expecting to spend the day sampling such skinny water.
The stream was only ankle deep where we began. Upstream were a handful of deeper pools and undercut banks where I expected the biologists to turn up a few good-sized native brookies. But as they slowly worked their way up, probing every inch of water and recording everything that went belly-up, I got excited. Not all those fish were young-of-the-year fingerlings. And not all were brookies.
When one of the biologists prodded a small plunge pool under a fallen log and a beautiful 18-inch wild brown trout floated up, my jaw dropped. To me, it was impressive. To the biologists, who survey small streams often, this was typical.
By the end of the day, I’d gained a new appreciation for those little trickles and their ability to harbor fish. And I realized that many of the tiny streams I’d taken for granted for so many years probably held some nice wild browns, too.
The area we surveyed had received a good bit of rain the previous week, but the stream was still barely six feet wide. As the biologists worked the water, I tried to guesstimate the quality of fish we’d find. There wasn’t one pool that really tripped my hot button or looked as though it might hold anything other than a scattering of tiny trout. Long, shallow riffles separated small, unimpressive pools. In short, it was the type of stuff you disregard on your way to better water.
The beauty of trout, though, is that they are where you find them. At times they’re ferociously territorial and live out their lives within small quadrants. Other times they’re more transient than a band of gypsies.
Later in the afternoon, the biologists moved on to a second stream they’d surveyed the year prior. That survey had produced enough trout to warrant a reassessment, to see if it would meet the requirements of a Class A water (40 kg of biomass per hectare). One of the biologists was especially excited about the resurvey because the first one had produced healthy numbers of wild browns up to 20 inches long. Again, this stream was about six feet wide, and in many places narrower than that. Another trickle.
As the crew worked upstream, beginning at the same point they first surveyed, their findings were considerably different. All those big fish were gone. They turned up a few browns in the 9- to 12-inch range, but none of the bruisers they’d anticipated . . . until they got to the really skinny water, maybe three feet wide. Suddenly, every pool with a little depth and good structure produced a wild brown over 16 inches. “That’s a relief,” one biologist said. “I was beginning to think these fish were going to make a liar out of me.”
According to the team, this was normal. The reason they clip a sliver of caudal fin on every trout they capture is so that they know which ones they’ve caught before when they resurvey a section. They often find that fish caught a day before have relocated.
After spending a day surveying these trickles, I decided that a nice-sized brown lived in every little bit of holding water. When I applied that approach to the streams I fish, and the trickles I’d walked right by in the past, my catch rates went up and I started picking up bigger fish than I ever had.
I also realized that, in trickles, big trout don’t always utilize the most obvious holding water all the time. Watching the stream survey was fascinating in that deep pools, even ones with desirable undercuts and root systems, didn’t necessarily guarantee big browns and, in fact, were often void of fish.
That doesn’t mean those pools went unused; lunker trout spend the majority of their time around other structure and move into the deeper pools to feed. The catch, of course, is that you never know when they’ll decide to feed, which is why it’s best to assume they’re always present.
In trickles, the holding water trout prefer is the kind that’s almost impossible for anglers, or other predators, to approach without being seen. It doesn’t have to be deep, but it must have structure that trout can slip under (usually long before you make a cast).
During my time following the survey crew, the most surprising find came in a stream only three to four feet wide and in a pool less than calf deep. When they probed a narrow gap under an overhanging rock, a hefty 16-inch wild brown floated into their net. I couldn’t believe that a trout of that size could thrive in such skinny water. It was the equivalent of finding a 50-inch muskie in your bathtub.