title: Potential for electropositive metal to reduce the interactions of Atlantic sturgeon with fishing gear.
abstract: Atlantic sturgeon (Acipenser oxyrhynchus) populations have been declared either endangered or threatened under the U.S. Endangered Species Act. Effective measures to repel sturgeon from fishing gear would be beneficial to both fish and fishers because they could reduce both fishery-associated mortality and the need for seasonal and area closures of specific fisheries. Some chondrostean fishes (e.g., sturgeons and paddlefishes) can detect weak electric field gradients (possibly as low as 5 Μv/cm) due to arrays of electroreceptors (ampullae of Lorenzini) on their snout and gill covers. Weak electric fields, such as those produced by electropositive metals (typically mixtures of the lanthanide elements), could therefore potentially be used as a deterrent. To test this idea, we recorded the behavioral responses of juvenile Atlantic sturgeon (31-43 cm fork length) to electropositive metal (primarily a mixture of the lanthanide elements neodymium and praseodymium) both in the presence and absence of food stimuli. Trials were conducted in an approximately 2.5 m diameter × 0.3 m deep tank, and fish behaviors were recorded with an overhead digital video camera. Video records were subsequently digitized (x, y coordinate system), the distance between the fish and the electropositive metal calculated, and data summarized by compiling frequency distributions with 5-cm bins. Juvenile sturgeon showed clear avoidance of electropositive metal but only when food was present. On the basis of our results, we conclude that the electropositive metals, or other sources of weak electric fields, may eventually be used to reduce the interactions of Atlantic sturgeon with fishing gear, but further investigation is needed.
authors.affiliation: Virginia Institute of Marine Science, P.O. Box 1346, Gloucester Point, VA, 23062, U.S.A.; Department of Ecology and Evolutionary Biology, The University of Michigan, 830 North University, Ann Arbor, MI, 48109-1048, U.S.A.
authors.forename: Ian
authors.initials: I
authors.lastname: Bouyoucos
authors.forename: Peter
authors.initials: P
authors.lastname: Bushnell
authors.forename: Richard
authors.initials: R
authors.lastname: Brill
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D055724:Electrophysiological Phenomena; D056727:Endangered Species; D005398:Fisheries / Q000295:instrumentation*; D005399:Fishes / Q000502:physiology*; D008670:Metals / Q000737:chemistry*
chemical_list: D008670:Metals
keywords: Chondrostean; Chondrosteo; ampullae of Lorenzini; avoidance; bycatch; campos eléctricos; captura incidental; electric fields; electroreceptores; electroreceptors; en peligro; endangered; evitación; lanthanide; lantánido; nado; swimming; Ámpula de Lorenzini