1. Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, Oregon 97331, U.S.A., e-mail: william.gerth@oregonstate.edu
2. 1574 Coburg Road, Box 108, Eugene, Oregon 97401, U.S.A.
3. 235 SW Central Avenue, Grants Pass, Oregon 97526, U.S.A.
4. Aquatic Biology Associates, 3490 NW Deer Run Street, Corvallis, Oregon 97330, U.S.A.