Scientific sampling effects: Electrofishing California's endangered fish populations

Standard methods used by biologists around the world for sampling fish popu lations and determining fish and habitat relationships primarily involve el ectrofishing. With the recent listings of mining fish and habitat relations hips primarily involve electrofishing. with the recent listings of coastal salmon and steelhead as threatened or endangered, one must ask how electrof ishing-induced injury to fish in rare populations relates to "take" under t he U.S. Endangered Species Act. Issues related to electrofishing are under discussion in California as federal and state agencies determine how to app roach permitting for monitoring and research activities in rivers containin g protected fish populations. Many problems have been discussed in the lite rature based on short- and long-term injury to individual fish from differe nt forms of electrofishing. To date no standard approach for this technolog y exists that will allow effective surveys without probable injury to some portion of the fish population. How electrofishing injuries made at the ind ividual fish level translate into population effects has not been adequatel y studied. In many areas of central and southern California, however, where the numbers of salmon and trout can be very small, and effective populatio n size is frequently less than 25 breeding pairs, accumulated effects due t o electrofishing may be significant. This paper reviews the electrofishing literature published during the last nine years. Based on this review and p ersonal experience, I belie iie fisheries biologists frequently electrofish without considering potential harm or alternative methods. Therefore, I su ggest the American Fisheries Society (AFS) develop a set of guidelines for least-invasive sampling methodologies, and adopt a policy on the ethical us e of electrofishing for use by federal or state agencies to regulate all el ectrofishing activities in habitats containing wild fish. I believe other n oninvasive study methods should be required in areas where it can be shown that electrofishing may significantly reduce a population's ability to pers ist.