Trout tracking

Our state fish, the Lahontan cutthroat trout (LCT), is a threatened species that exists in native habitat in only two places: Independence Lake, 12 miles north of Truckee in the Northern Sierra, and Summit Lake in northwestern Nevada.

The Nature Conservancy (TNC) and the U.S. Geological Survey (USGS) started a program to track the population of LCT in Independence Lake. TNC sends out invitations to groups of Trout Unlimited in the area to come fish the lake. When they catch a LCT, the USGS tag it and then release it back into the lake.

“What we do is send out invitations to people we know have experience catching fish,” said TNC’s Eastern Sierra Nevada program director Chris Fichtel. “With a fish like this that’s so rare, we want to be careful. We want to have people who really know how to fish and know how to handle a fish and do it carefully and not hurt them.”

TNC has a preserve of about 2,300 acres that surrounds the lake and had been working to prevent aquatic invasive species from being brought into it by providing new motorboats and kayaks for public use at the lake. These boats are now being used for this program.

TNC and USGS have brought fishermen to the lake for this program twice so far—last year and in June. Fichtel said they will be doing this again on July 20 and in late September.

“We have great fun,” Trout Unlimited member Bill Copren said. “And it’s interesting to see how they deal with the fish, how they measure them and the computer stuff with the tags. … Before this, I had paid guides to take me to Independence Lake. It’s a spectacular place.”

LCT have been re-introduced into other lakes, like Pyramid Lake, but they have so far been unsuccessful at spawning in these places. Fichtel said the population in Independence Lake is especially important because it exists on its own, although it has dropped down to numbers as low as 50 adult fish.

“It’s a native trout to this particular part of the Western United States,” Fichtel said. “This is part of the natural heritage, especially where you find places where they never disappeared from.”

One of the reasons this population information is so important is that tracking how many females there are allows the USGS to know about how many eggs are laid. And after tracking the number of young, they can figure out the success rate of reproduction, according to Fichtel.

“One of the problems the USGS found out about this population was a non-native fish was in there—well, there are three non-native fish, but only one has so far been a problem, and that’s the brook trout,” Fichtel said. “The Lahontan Cutthroat Trout in Independence Lake never had a predator other than bears and things like that—never a fish predator. When brook trout got introduced they would come into the stream, and they’re voracious predators. They’ll eat the young of the Lahontan Cutthroat Trout.”

Because of the problem with the brook trout, the USGS has been removing as many as they can catch each year from Independence Lake since 2005.

“Monitoring of the Lahontan Cutthroat Trout has shown that since that program began—the brook trout control—the numbers of the Lahontans have gone way up,” Fichtel said. “And they’ve stayed fairly high. They’re getting better; they’re on the right trajectory.”