Integrated, Multi-Sensory, Behavioral Guidance Systems for Fish Diversion
Behavioral Technologies for Fish Guidance: American Fisheries Society Symposium
American Fisheries Society
Behavioral guidance includes, at least in principle, both repulsion and attraction. Although they are usually used separately, this paper encourages use of both to develop integrated guidance systems using a multi-sensory approach to fish diversion. Research in the 1940s and 1950s with adult salmon and prototype fish ladders emphasized attraction of fish to turbulent currents. As a result, attraction flows to entice fish to fish ladder entrances are now a usual feature of adult dam bypasses. In contrast, techniques for fish repulsion have dominated research on guidance of fish away from risks of water intakes in the hydropower and steam electric utility industries and agriculture (irrigation). The objective has been to find devices that would guide fish away from the hazards of entrainment and impingement. Thus, strobe lights, sound, bubble curtains, electric fields, and the like have been evaluated as ways to repel fish from intakes. None of these technologies has become an industry standard and all are usually considered experimental. I encourage consideration of both repulsion and attraction together to both guide fish away from a hazard and attract them toward am alternative safe location. In addition, more than one technology for either (or both) may be usefully combined. Fish bypasses at dams, for example, could use strobe lights or ultrasound to divert (repel) fish from a trajectory aimed at turbine entrances and concurrently use attraction flows to entice them toward surface bypass entrances, Behavioral and structural technologies can be integrated as hybrid systems. Innovative combinations tailored to a site and specific behaviors of the fish to be guided are likely to show better overall results than one technique alone.