Glacier National Park works to save Bull Trout (part 1 of 2)

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By Tom Sentner

A juvenile bull trout swims through the water above a juvenile westslope cutthroat trout in Glacier National Park.           Photo courtesy of USGS

 

Immersed in a cathedral-like forest of tall trees in the cool quiet of morning, my thoughts are interrupted upon hearing an unfamiliar sound behind me – horse hooves. I hike the trail to Quartz Lake, where I’ll interview Glacier National Park’s fisheries crew. I fell behind the lightning-paced crew, and now I’m falling behind the mules packing in their supplies, even though the animals are loaded down with inflatable kayaks, nets, fuel and other supplies. Fisheries management work in Glacier’s backcountry is fraught with logistical challenges, and I start to think maybe I shouldn’t have packed my inflatable bedroll and those heavy cans of chili.

Finally, I reach Quartz Lake. The crew is busy re-packing the mules with the previous week’s worn nets and empty gas containers. Their newly acquired boat, flown in by helicopter last year, sits anchored on the glassy water in front of imposing Vulture Peak. There’s a good reason why Fisheries Program Manager Chris Downs focuses much of his team’s efforts here. This quiet lake, ringed by dense, coniferous forest, is a key battleground in the fight to save some of the last viable bull trout populations and habitat in the Northwest.

Bull trout are the top native predators of the upper Columbia River system. They have a very low thermal tolerance, meaning they require extremely cold water to survive. This makes bull trout vulnerable to warming stream temperatures, which are predicted to continue to rise as the climate warms. They are also a migratory species that moves from lakes and rivers into smaller tributaries to spawn, making them additionally vulnerable to the loss of suitable stream habitat. Nonnative lake trout, which spawn directly in lakes, displace bull trout through predation and competition for food. These combined threats create a challenging conservation puzzle for Glacier’s fisheries team.

Glacier National Park records show that concern about the invasive nature of lake trout was voiced in the 1930s and again in the 1960s by fisheries biologists studying Glacier’s lakes and streams. These concerns proved to be tragically valid. Lake trout, which had been intentionally introduced to Flathead Lake in 1905, gradually made their way into the upper reaches of the watershed, including lakes on Glacier’s western slopes. Bull trout populations that thrived in these waters for thousands of years crashed rapidly, with dramatic declines often appearing within 30 years after initial detection of lake trout. Quartz Lake is unique among these lakes. When lake trout were first documented in Quartz Lake in 2005, the lake still contained a healthy bull trout population. Biologists feared that if immediate action wasn’t taken, the bull trout population would essentially disappear, mirroring what had occurred in all of Glacier’s other large lakes west of the Continental Divide.

To save the Quartz Lake bull trout population, focused efforts have been made to remove lake trout with gill nets, simulating the commercial fishing pressure that historically caused the collapse of lake trout fisheries in the Great Lakes. These efforts also are being applied at nearby Logging Lake, where the U.S. Geological Survey is testing lake trout netting as a long-term strategy for bull trout recovery. In addition, park managers and USGS researchers teamed up to try something new and experimental: moving juvenile bull trout upstream from Logging Lake to Grace Lake to try and establish a new bull trout population.

 

Tom Sentner is a graduate student and aspiring nature writer enrolled in the University of Montana’s Environmental Studies program. 

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