Henrys Lake’s smaller population of large trout is a good sign for anglers

There are fewer fish in Henry’s Lake this year, but they are getting bigger, which is great news for Henry’s fanatics.

Idaho Department of Fish and Game biologists conducted their annual gillnet surveys earlier during spring and found a fish population that

should make anglers very tickled.

“The surveys show fish size have been going up, and the fatness of the fish is going up,” said Dan Garren, fisheries manager in the Upper

Snake Region. “That is good news for the folks who love Henry’s.”

Henry’s Lake in the northeast corner of Idaho near the Montana border is one of state’s most prized fisheries and famous for its trophy trout.

Each spring, biologists set 50 gillnets in the lake over a two-week period. The nets are set in the evening and retrieved in the morning.

The number, size and species of fish is tracked, giving biologists an idea of population trends in the famed lake.

This spring, Garren’s team found 9.5 fish per net, which is down from 12 fish per net last year. The long-term goal is 11 fish per net.

Although it sounds counter-intuitive, fewer fish is great news for anglers. Simply put, fewer fish means bigger fish and that, generally, is what anglers expect from Henry’s.

“If you have a lot of fish in the lake, the available resources are spread thinner,” Garren said. “There basically aren’t enough groceries

for all those mouths.”

For the past decade, natural spawning on Henry’s has been improving because of habitat work on critical spawning tributaries. That trend

increased trout numbers, but it also led to smaller fish. Smaller fish make Henry’s aficionados unhappy.

To trim the lake’s trout population, Fish and Game has decreased its stocking. Again, the goal is fewer — but bigger — fish.

“The gill-nets show we are meeting that goal,” Garren said.

From the gill-nets, the department learned a couple of interesting things, in addition to the growing size of the lake’s trout.

First, the most prevalent species in the lake is Yellowstone cutthroat. They make up 55 percent of the trout population. The

average size was 15 inches but biologists had some cutts over 20 inches.

The second most prevalent species is rainbow-cutthroat hybrids, which make up 24 percent of the population. The average size is 19 inches,

although Fish and Game caught hybrids longer than 25 inches.

Brook trout make up 21 percent of the population. The average length is 16 inches but biologists caught several brookies that topped 20 inches.

Biologists also use the nets to track chubs. This year, Garren said the chub population is falling. The nets show the chub population is

half last year’s number and the lowest number since 2012. He said chubs have no influence on the number of trout in the lake because

they feed on different things.