Fisheries Restoration by Gretchen Schenk During the 2002 field season, the fish crew will reintroduce native Bonneville cutthroat trout (BCT) to Strawberry and South Fork of Big Wash creeks, monitor macroinvertebrates, and conduct a renovation treatment on Snake Creek. This treatment will eliminate nonnative brook trout from about four miles of the creek upstream of the pipeline so that BCT can be reestablished. Why treat? Fisheries restoration projects often require removing nonnative fish that are present in the stream and replacing them with native fish. Tools to do this include increased angler pressure, electrofishing and chemical treatments. Increased angler pressure only works if all the fish are of catchable size. Since most streams have young-of-the-year present that are only two to three inches long, this alternative is rarely feasible. Electrofishing, which uses an electrical current to stun fish, can be used to remove large numbers of fish. However, many fish can sense the current coming and hide deep under overhanging banks or in other inaccessible areas where the netters cannot reach them. Thus for many fisheries restoration projects, chemical renovations are the only sure way to remove all the nonnative fish. Two chemicals are commonly used, rotenone and antimycin. Great Basin National Park used rotenone to treat Strawberry Creek in 2000 and plans to use antimycin in 2002 to treat Snake Creek. Rotenone Rotenone naturally occurs in the roots of tropical plants in the bean family (Leguminosae) in Mexico, Central and South America, Australia, Oceania and southern Asia. People in these areas have used rotenone for centuries to capture fish. Fisheries managers in North America began to use rotenone as a piscicide (fish killer) in the 1930s on lakes and ponds, and then in the 1960s on streams. Rotenone works by inhibiting a biochemical process at the cellular level that inhibits fish to absorb oxygen in the blood. It provides rapid results and can be used in large river systems. The downside of rotenone is that it creates a temporary loss of potable water supplies and recreational opportunities, has a large effect on aquatic insects, can repel fish, and does not kill fish eggs until the shell ruptures at hatching. Antimcyin Antimycin is an antibiotic produced by molds of the genus Streptomyces that is found naturally in forest soils. It was first used as a piscicide in 1963, and is favored because it is not detected by fish and can be applied in cold alpine waters in parts per billion (ppb), which is one thousand times less than the amount needed for rotenone. Antimycin is a selective piscicide, meaning that it affects some fish more than others. It is frequently used to clean catfish ponds of unwanted fish, since catfish are very resistant to it. Antimycin works by entering the fish gills and inhibiting fish to absorb oxygen at the cytochrome level, which takes longer than at the cellular level. The downside of antimycin is that it breaks down rapidly in the stream, so fisheries managers have to ensure that enough is present to be effective. Fisheries Restoration in Great Basin National Park In September 2000, Great Basin National Park in cooperation with the Nevada Division of Wildlife (NDOW) used rotenone to chemically renovate Strawberry Creek. Macroinvertebrate populations immediately plummeted following the treatment, and a year later populations had recovered to about 70% of pre-treatment numbers. Due to concerns about rotenone's effects on macroinvertebrate populations, the amount of time rotenone takes to break down (weeks compared to hours for antimycin), and about safety (antimycin is safer to apply than rotenone), Park staff decided to use antimycin for the next treatment. Antimycin is the piscicide of choice for mountain streams in the National Park Service, used by Crater Lake, Rocky Mountain, and Great Smoky Mountains National Parks. Prior to the Snake Creek treatment in August, the Park will sponsor a workshop in conjunction with the American Fisheries Society to train fisheries managers in Nevada and Utah on how to use antimycin. Great Basin National Park will monitor macroinvertebrates before and after the Snake Creek treatment to determine how fast aquatic insects repopulate the stream. We expect that the populations will rebound quickly, as they did at Great Smoky Mountains National Park, where macroinvertebrate numbers returned to pre-treatment levels only five months after an antimycin application. The results with Snake Creek will be compared to those of Strawberry Creek to determine how macroinvertebrates rebound after applications of each chemical. Monitoring is also done to find out when the post-treatment macroinvertebrate population reaches 75% of the number and diversity of pre-treatment population. Once this goal has been obtained, then the food base should be sufficient to support a fish population, and Bonneville cutthroat trout will be reintroduced. Midden Table of Contents