Influence of a low intensity electric sea lion deterrence system on the migratory behavior of fishes in the upstream migrant tunnel (UMT) at Bonneville Dam.

Predation by pinnipeds, such as California sea lions (Zalophus alifornianus), Pacific harbor seals (Phoca vitulina), and Stellar sea lions (Eumetopias jubatus) on returning adult Pacific salmon (Oncorhynchus spp.) in the Columbia River basin has become an increasing concern for fishery managers trying to conserve and restore threatened and endangered runs of
salmonids. As a result, Smith-Root Incorporated (SRI; Vancouver, Washington) proposed a demonstration project to evaluate the potential of an electrical array to deter marine mammals (SRI 2007). The objective of their work was to develop, deploy, and evaluate a passive, integrated electric and sonar array that selectively inhibits upstream marine mammal movements and predation, without injuring pinnipeds or affecting anadromous fish migrations. However, before such a device could be placed in the field, concerns by regional fishery managers about the potential effects of such a device on the migratory behavior of or injury to Pacific salmon, steelhead (O. mykiss), Pacific lampreys (Entoshpenus tridentata), and white sturgeon (Acipenser transmontanus) needed to be addressed.