Brookies Get a “Leg” Up

Earlier this week, I had a chance to talk with Jim Habera, wild trout biologist for the Tennessee Wildlife Resources Agency’s Region IV.

For many years Habera has conducted annual surveys of the region’s streams to inventory the resources and assess the management policies. Part of those surveys involves a group of streams where populations of rainbows and brook trout are present.

Ongoing research has revealed some interesting dynamics between the native brookies and the introduced rainbows, and it seems that weather patterns are a major factor.

“Gentry Creek is a monitoring station,” Habera said, “I’ve been doing this since the early ’90s, and we’ve been able to watch the relative abundance of the brook trout change over time because they’re mixed with rainbows in that area.

“One year, it got down below 50 percent when we’d had some high flows. But here with this drought – drought’s actually good, if you can call it that, for brook trout if they’re mixed with rainbows. Drought seems to be a lot harder on the rainbows in these mountain streams.”

“I think it’s just because that’s what happens here in these Southern mountains,” Habera went on to explain. “You get these droughts, and our native brook trout are adapted to that and they fare a little better than the rainbows do. So, what we’ve seen in Gentry Creek over these past years, is a shift in the relative abundance of brook trout.

“In fact, when we did [this year’s survey] back in June, Gentry is 100-percent brook trout. [We] didn’t get a single rainbow in an area that back in 1998-99 had a relative abundance of brook trout around 30-35 percent. In other words, 70 percent of the fish were rainbow.”

The numbers began to change significantly with the onset of the last drought.

“It really started coming up in about 2004-05,” Habera said, “and steadily built up. In 2009, it’s 100-percent brook trout right now in that site. That’s pretty clear-cut to me how those things respond to droughts and floods.
“Now, if we have a bunch of wet years in a row I think you’ll see those rainbow numbers start building back up, but dry years definitely benefit the brook trout populations.”

Habera went on to point out that if rainfall stays near normal levels, it will still be several years before the abundance of fish returns to normal and the population holds a good proportion of larger fish.

NOTE: Jim Habera will present a program on TWRA’s Management Plan for Holston River this Saturday during The South Holston Fly Fishing Fest at Rivers Way on Stoney Hollow Rd. in Bluff City. I’ll also be part of the program and will be discussing fishing spinner falls. Hope to see you there.