Thousands of lake trout netted from Logging Lake in first year

Glacier National Park’s Logging Lake is brimming with non-native lake trout, biologists have found. In 2015, biologists from the U.S. Geological survey netted 2,158 lake trout from the remote North Fork water.

“That’s a lot of fish,” Vin D’Angelo, fisheries biologist with the USGS said.

Initial netting last spring brought worries that the entire lake was full of lake trout and little else. They only caught 10 suckers, but hundreds of lake trout. The lake trout are killed and their air bladders are punctured so they sink back to the bottom of the lake, which avoids any conflict with bears and other scavengers.

But fall netting caught 864 suckers, D’Angelo noted. The idea isn’t to catch suckers, which are a bait fish, he noted, but at least biologists know they’re in the lake in healthy numbers. In fact, Logging Lake has turned out to be a fairly diverse body of water compared to other North Fork lakes. In addition to suckers species, it has a healthy population of westslope cutthroat trout, northern pike minnows and mountain whitefish. The lake trout don’t eat many cutts, because lake trout generally live in water that’s 50 to 70 feet deep, while cutts are a surface feeding fish.

Logging Lake is about 4.5 miles east of the Inside North Fork Road and only accessible by trail. Supplies for the netting effort, including the boat, nets and motors, were flown in by helicopter. Biologists hikde in.

What the lake doesn’t have much of anymore is bull trout. Once a robust bull trout fishery, the bulls today are all but gone. Redd surveys in the inlet spawning stream found no redds last year. A redd is a spawning bed. Biologists can estimate the health of the bull trout population by counting redds. Lake Trout were first found in Logging in 1984 and have taken over the ecosystem since then.

While the netting doesn’t target bull trout, there still is some accidental capture of bull trout. But D’Angelo said they caught just seven bulls — two adults and five juveniles.

“Which is incredibly low,” he said.

Unlike bull trout, which spawn in streams, lake trout spawn in lakes. So biologists tag adult fish with radio transmitters and then follow their movements in the fall. The fish, in turn, lead biologists to spawning areas where they can be more easily netted.

At first, biologists were worried that the lake trout in Logging were spawning lake-wide. But after further study, they are finding specific spawning sites, including one key site near the Adair Creek campground, D’Angelo said.

He said they fully expect to catch even more lake trout this year, as the boat they have can haul a longer net than what’s been used in Quartz Lake, where a similar effort has been ongoing. They’ll start netting in May for a few weeks and then stop. They’d like to be out of the lake by the time loons start nesting, he said, as to not disturb the birds. They’ll then do another round of netting in the fall. They don’t net in the summer months.

The idea is to eventually suppress the lake trout population to the point where the bull trout can recover. Biologists have also stocked more than 100 juvenile bull trout from Logging Lake into Grace Lake, which is directly upstream from Logging. Grace Lake is protected from lake trout migration by a waterfall. It previously held only Yellowstone Cutthroats.

The hope is bull trout will find Grace Lake to their liking, and then perhaps, eventually, they can be restocked into Logging Lake, restoring the native fishery.