Forest Service shocks fish to conduct survey

Chris Lemmers has been shocked more times than he can remember. As a fish surveyor for the Forest Service, his job is to walk or boat the rivers, streams and creeks of the region with an LR-24 Electrofisher, stunning fish and sometimes himself with electricity.

"It's not bad," Lemmers said. "But you can definitely feel it."

When the fish feel the electricity, their involuntary reaction is to swim from their hiding places in the rocks, reeds and banks of the waterways.

Lemmers and crew net the dazed fish, put them in a bucket, count and record their species and lengths before releasing them unharmed.

"You do this long enough, and you can kind of see 'Oh, there will be a nice fish in there," Lemmers said as he peered into a rocky outcropping in the Upper Truckee River near the airport.

Currently surveying 12 to 15 miles of the Upper Truckee, Lemmers and Forest Service aquatic biologist Richard Vacirca, along with help from a revolving team of three, are collecting data that will impact the way the new channel for the river is sculpted and inform other management decisions in the future.

"The purpose of the project is to understand what we've got," Vacirca said.

And that doesn't mean just counting the different types of fish. The crew has to assess the fish stock, observe the different types of habitats, record where the native fishes are occurring in the greatest frequency and note unusual finds like giant crayfish or native freshwater mussels.

Other methods of fish surveying do exist, but they aren't as well suited to the area as electrofishing. Seines, long fence-like nets, can be used, but the Truckee's varying depth makes it difficult. Gill nets are another possibility, but they are typically fatal to the fish. Snorkeling is a fun and easy way to count fish, Vacirca said, but in this area fish hide so well they're often too difficult to spot.

The Electrofisher is a box-like backpack connected to a long wand shaped like a metal detector. The operator waves the wand underwater, delivering a 275-volt current through the river. The distance the electricity travels depends on the conductivity of the water, which, in turn depends on factors like temperature, depth and murkiness. Rubber waders protect the crew members from the electricity, but a slip of a hand or a leak in the waders can reward the offender with a sudden jolt.

In the Upper Truckee, the crew has been finding a wide variety of fish, from native species like dace, cui-ui, suckers, Lahontan redside shiners and scolpin to non-native species like rainbow trout, brown trout, bullheads and bluegills.

"All of these (native) fish evolved with Lahontan cutthroat trout as the only predator," Vacirca said. "What my hypothesis is at some point the invasive species have depressed the natives populations. To what point, I'm not sure. Hopefully, this data will help us understand that."

Not much data exists on the native fish populations in the area, Vacirca said. As well as impacting immediate management decisions, this new information will give organizations something to compare to in the future.

The crew cuts the river into 100-meter sections. As they sample each section, a pattern of where certain species are occurring and in what frequencies will emerge. Translating this pattern into usable information is already underway. When the new channel near the airport for the Upper Truckee River opens later this year, an aquatic designer will use the findings to replicate the elements of the habitat- the rocks, the sunken wood, the reeds, the bottom contours, the cover- of the fishes that live in that area.

"In channel restoration, you've got to know your species because you need to know what they need," Vacirca said.摥