Removing & restoring fish

Fisheries biologist Matt Kulp and others electroshock a river to collect Brook trout.

Fisheries biologist Matt Kulp and crew electroshock native Brook trout.

NPS photo.

This day on Lynn Camp Prong was one of many in a long-term effort to treat the Smokies’ streams for non-native fish. The antibiotic Antimycin is toxic to all fish, including the non-native brown and rainbow trout. It interferes with the oxygen transfer at the cellular level in a fish’s body, eventually shutting down internal organs.

In preparation for these treatment days, fisheries biologists waded through miles of deep pools and hidden pockets to find brook trout and other native fish such as the blacknose dace that they wanted to save in Lynn Camp Prong and its tributaries. They electroshocked the native fish—stunned them with a low amplitude current—and gathered them all in holding tanks, which they then transported to a “foster” stream in the same watershed that had been treated four years earlier for this purpose. There the brook trout would wait through the winter until they could be released once again to Lynn Camp Prong.

People have long managed waterways for certain species. Even the original introduction of the non-native brown and rainbow trout was a kind of management: before the Park existed, people released the fish into Smokies’ streams so anglers would have more fish to catch.

A Smokies angler casts for fish in the 1930s.

Smoky Mountain streams have long been excellent fishing spots. Here, an angler casts for fish in the 1930s.

NPS archive photo.

They didn’t realize that the introduced fish would outcompete—take over habitat and food sources from—the native brook trout. Fewer native fish survived to breed, and those that did existed in increasingly isolated populations in marginal habitats, often at high elevations where pH was declining most rapidly.

In 1987 the park began restoring brook trout, and in 2000 began treating streams with Antimycin. Because this antibiotic has been accepted as relatively safe and can be neutralized when biologists want to treat a small area or for a short amount of time, National Parks and other protected areas choose it to treat their streams and lakes. The EPA representative at the Lynn Camp Prong treatment was there to observe and gather information about its field use in a protected area.

Of course, moving fish, treating streams, and restoring fish is only part of the whole brook trout restoration story. Read on for more information about how biologists are coming to understand the movements and backgrounds of the brook trout on page 3: Who’s who in fish: genetic research.

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