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 Mountain yellow-legged frog at Kings Canyon National Park, California Roland Knapp
Harold Werner
Back to Chapter 6: Restoration Articles Breathing space at Lechuguilla Cave By Jason M. Richards National Park Service to share science role in Everglades restoration By Thomas Van Lent California condors return to the Colorado Plateau By Elaine Leslie Wolf restoration in Yellowstone successful beyond expectations By Douglas W. Smith, Roger J. Anderson, and Julie Mao Wetland and stream restoration at Elk Meadow in Redwood National Park By James H. Popenoe Other Developments Award-winner Profile - Botanist honored with first professional excellence award Preservation of the Fort Dupont stream Coastal dune restoration at Point Reyes Bonytail restoration continues Maintenance staff help restore native fish at Point Reyes |
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 By Harold Werner The mountain yellow-legged frog, Rana muscosa, is endemic to the Sierra Nevada and some mountains in southern California. It is the only large frog in the high Sierra and an important part of the alpine and subalpine environment where lakes are naturally free of fish. Historically, backcountry visitors could see hundreds of these frogs along the shores of individual lakes, and thousands of their large tadpoles could be seen swimming in the clear water. Today they are rarely observed. The mountain yellow-legged frog is a rapidly declining species in the Sierra Nevada. The U.S. Fish and Wildlife Service has found sufficient evidence to warrant its designation as a federally endangered species. Science has shown that introduced fish are a primary cause of their decline in some portions of their range, and that frogs will repopulate areas after fish have been removed if adjacent donor populations exist. Other stressors also threaten the species’ survival. Diseases, particularly chrytrid fungus infections, kill large numbers of frogs. Growing evidence suggests that airborne pesticide drift from the San Joaquin Valley may be a serious cause of decline in large portions of their range. Science is attempting to understand these threats but is still far from providing effective tools for species management. The seriousness of the decline prompted the park to explore options for meaningful recovery where sufficient information supported by research was available. The park lacked the scientific information needed to develop a comprehensive long-term program, but wanted to take some immediate actions toward restoration. Four alternative recovery prescriptions were developed, and an environmental assessment was prepared. In developing the alternatives, staff focused on proven methods and avoided actions that were most likely to generate controversy, such as the use of fish poison. Though labor-intensive, much of the public support came from park staff’s willingness to use gill nets to eradicate introduced fish from lakes. This approach effectively eliminated social and biological concerns associated with the use of fish poison. Professional herpetologists identified sites with a high probability for success. The park received 167 comments with 80% support for the preferred alternative, clearing the way for removal of fish from 11 lakes and associated stream segments. A crew began removing fish from lakes using gill nets on June 26, 2001. By the end of the field season, they had removed 1,665 fish from 6 of the 11 lakes. The effort involved 14,479 net-hours (1 net hour = 1 gill net used for one hour). The crew removed 81 additional fish from adjacent streams using an electrofisher, a device that electronically stuns the fish. Other fish were herded downstream into the lakes, where they could be captured in gill nets. Removed fish included 937 eastern brook trout and 728 hybridized golden trout. Gill nets consisted of six panels with mesh sizes from 10 to 38 mm, allowing capture of all sizes of fish except for that year’s young. The target was to remove all fish of breeding age from lakes where fish were not native. During the next one to two years, the remaining young fish can be removed from the lakes as they grow. In conjunction with fish removals, the crew is monitoring frog populations at targeted sites to document recovery. The restoration team found mountain yellow-legged frogs in the vicinity of all restoration sites. Based on previous research, recolonization is expected to begin even before all fish have been removed. In the meantime, information is being collected for a programmatic environmental document that will examine alternatives for managing all human-related threats to frogs in the park. |
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This material is from Natural Resource Year in Review--2001, published by the National Park Service, U.S. Department of the Interior, in May 2001 (publication D-2255) /YearInReview/yir/yir2001/06_restoration/06_1_werner_KICA.html Last Updated: |
