 |
Wednesday, May 28, 2008 - 9:30 AM
395
Methods for evaluating threatened and endangered snails in the middle snake river, idaho
William H. Clark1, Leska Fore2, and Barry M. Bean1. (1) Environmental Affairs, Idaho Power Co., 1221 West Idaho Street, Boise, ID 83702, (2) Statistical Design
In 1992 the U.S. Fish and Wildlife Service (USFWS) listed four gastropods in the Middle Snake River, Idaho, USA, as endangered and one as threatened. Of these, two were in the section of river which has five hydroelectric facilities in the relicensing process with the Federal Energy Regulatory Commission (FERC). The Bliss Rapids Snail (BRS), Taylorconcha serpenticola, was listed as threatened and the Idaho springsnail (ISS), Pyrgulopsis idahoensis (now P. robusta) was listed as endangered. A settlement agreement was reached with Idaho Power Company, USFWS, and FERC in 2004 to study the impacts of power production on these two taxa. Since little was known about these snails, a five year study was begun to study the depth distribution of the snails in the river and the potential impacts of river stage fluctuations on them. BRS is found on the undersides of cobbles and boulders so was mostly studied by a cobble count method. ISS lives in more depositional river reaches and was sampled with a suction dredge. Additional studies involved laboratory and field desiccation studies, snail abundance in river habitats and the distribution of those habitats, spring and tributary surveys for additional populations, and a risk assessment utilizing all information available.
Web Page: snails, sampling, ESA