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.

What makes fish vulnerable to capture by hooks? A conceptual framework and a review of key determinants

“…Records of shark depredation of electronic biologgers suggest electroreceptive attraction (Kerstetter, Polovina, & Graves, 2004) and Porsmoguer, Bănaru, Boudouresque, Dekeyser, and Almarcha (2015) found that magnets on hooks increased catch rates of blue shark (Prionace glauca; Carcharhinidae). Other recent research demonstrates deterrent effects of electropositive metals, magnets, and semiochemical repellents on by-catch of sharks and sturgeon, although results are temperature-and species-specific and may be superceded by social cues when fishes aggregate (Bouyoucos, Bushnell, & Brill, 2014;Brill et al, 2009;Hutchinson et al, 2012;O'Connell, Stroud, & He, 2012;Robbins, Peddemors, & Kennelly, 2011).…”

Review of the biology, fisheries, and conservation status of the Atlantic Sturgeon,(Acipenser oxyrinchus oxyrinchusMitchill, 1815)

“…comm.) or incorporation of electropositive metals into fishing gear (Bouyoucos et al., ) can help to reduce bycatch of AS in riverine fisheries.…”

Raised‐Footrope Gill‐Net Modification Significantly Reduces Subadult Atlantic Sturgeon Bycatch

“…Gear modification investigations to limit the bycatch of Atlantic Sturgeon have ranged from the use of experimental nets (Fox et al 2013; Pingguo and Jones 2013) to the incorporation of electropositive metals for behavioral deterrence (Bouyoucos et al 2014). Musick and Hager (2007) found that increasing twine size, augmenting the hanging ratio, and removing tie‐downs all significantly reduced the retention rate of captive Atlantic Sturgeon under controlled or captive conditions.…”