The use of baited underwater video to monitor fish behavior in response to boat motor noise

Abstract

Human generated noise affects hearing, movement and communication in both aquatic and terrestrial animals, but direct natural underwater behavioral observations are lacking. Baited underwater video (BUV) equipped with hydrophones were deployed inside and outside a marine reserve to observe fish behavior during motorboat transits. BUVs were effective in attracting fishes to within camera range with fish numbers plateauing within 20 minutes of deployment. The fish assemblages were dominated by snapper (Pagrus auratus). A boat equipped with a 60 HP 4 stroke engine made two passes past the BUV and then circled the area three times. Video was analyzed for fish number, interactions with the bait jar, and intraspecific interactions. Preliminary results suggest that fishes inhabiting the protected area showed less response to motorboat transits compared to fishes outside the area. The experiments suggest that anthropogenic noise in the marine environment can effect fish behavior and that BUVs provide the capability to monitor these interactions.