Behavioral and Physiological Response of White Sturgeon to an Electrical Sea Lion Barrier System

Abstract

Action agencies have encouraged the development of a modified electrical fish barrier system to deter upstream movements of California sea lions Zalophus californianus as a means to reduce their predation on returning adult Pacific salmon Oncorhynchus spp. within rivers along the West Coast of North America. Given that the barrier system does not discriminate which species will experience electrical shock, we studied the potential effects of the sea lion barrier on the survival, behavior, physiology, and injury of white sturgeon Acipenser transmontanus. Fish subjected to acute electroshock had high survival (100%). Conversely, fish that became entrained within the electric field and therefore experienced chronic electroshock had lower survival (93%). White sturgeon altered their behavior by spending significantly more time avoiding the area over the barrier when electrical power was applied as compared with controls. Fish that experienced acute electroshock spent more time remaining motionless, presumably recovering from physiological disturbance. Our results indicate that white sturgeon had significantly higher plasma lactate than controls and that lactate remained at elevated levels for at least 4 h after electroshock. Plasma glucose, ion concentrations (chloride, sodium, and potassium), and indicators of cell damage (plasma hemoglobin and enzyme activity of aspartate transaminase) did not differ between electroshocked fish and controls. We did not observe any notable hemorrhages or notochord injuries in white sturgeon that experienced electrical shock. Our results suggest that the location for the electrical barrier system should be rigorously examined before barrier deployment and that the dates, frequency, and duration of use should be further refined to ensure that negative effects on nontarget species such as white sturgeon are minimized.

Effects of Electric Barrier on Passage and Physical Condition of Juvenile and Adult Rainbow Trout

“…Output voltage had no effect on rainbow trout passage. Pulse widths and voltages used in the study were relatively low compared to settings tested in previous studies (Ostrand et al 2009;Johnson and Miehls 2013;Johnson et al 2014), yet the range of settings tested here inhibited passage of various sizes of rainbow trout (52-410 mm FL). However, higher incidences of juvenile passing occurred at lower pulse widths.…”

“…Electric barriers have been used for nearly a century to inhibit the movement of targeted nuisance fish species (Baldwin 1921). However, the effects of electric barriers can be indiscriminant; nontarget species may also be affected (Ostrand et al 2009). Barriers designed for movement inhibition of target species have been shown to also inhibit movement and cause stress, injury, and mortality to multiple species of nontarget fish (Swink 1999;Ostrand et al 2009;Johnson et al 2014).…”

“…However, the effects of electric barriers can be indiscriminant; nontarget species may also be affected (Ostrand et al 2009). Barriers designed for movement inhibition of target species have been shown to also inhibit movement and cause stress, injury, and mortality to multiple species of nontarget fish (Swink 1999;Ostrand et al 2009;Johnson et al 2014). As a result, there is growing concern about the negative effects of electric barriers to nontarget species of concern (e.g., to migration patterns of native fishes such as salmonids, Fausch et al 2009).…”

GUIDING OUT‐MIGRATING JUVENILE SEA LAMPREY (PETROMYZON MARINUS) WITH PULSED DIRECT CURRENT

“…Vertical electrodes produce an electric field that varies on the horizontal axis with intensity increasing closer to the line electrodes (Johnson et al, In Review). Bottom-mounted horizontal electrodes produce an electric field that varies on the vertical axis with intensity increasing closer to the substrate (Ostrand et al, 2009). Therefore, an advantage of vertical electrodes is that they produce an electric field that varies minimally with water depth, whereas horizontal electrodes produce an electric field that weakens near the water surface.…”

Effect of Waveform and Voltage Gradient on the Survival of Electroshocked Steelhead Embryos and Larvae

“…Electricity is used as a tool to monitor fish populations (McMichael et al 1998) and to limit the distribution of or remove nonnative fish deemed harmful (Moore et al 1983;Verrill and Berry 1995;Kulp and Moore 2000;Pacas and Taylor 2015). Although electroshocked fish can exhibit behavioral changes (Mesa and Schreck 1989;Ostrand et al 2009) and occasionally even die (Hudy 1985;, strong interest in how fish react to electricity developed when sublethal injuries to adult and juvenile steelhead Oncorhynchus mykiss were frequently observed after electrofishing (Sharber and Carothers 1988;Ainslie et al 1998). Managers have also expressed concern that repeated electrofishing may harm endangered fishes and their embryos (Muth and Ruppert 1997;Nielsen 1998;Bohl et al 2009).…”