Sound, chemical, and light detection in sea turtles and pelagic fishes: sensory-based approaches to bycatch reduction in longline fisheries

Mortality due to capture in longline fisheries has been implicated as a significant factor contributing to population declines for several species of threatened or endangered sea turtles. Identification of methods to reduce or prevent sea turtle bycatch is a high priority for fisheries managers and a necessary component of conservation efforts. One approach to reducing sea turtle interactions with longline fisheries is to take into account the behavior of sea turtles and the factors that lead them to interact with fishing gear. An understanding of the sensory cues that attract sea turtles to longline gear could help guide efforts to develop gear and bait that is less attractive, non-detectable, or even repellent to sea turtles. This paper presents a review of morphological, physiological, and behavioral studies conducted to assess the auditory, chemosensory, and visual capabilities of sea turtles, as well as the large pelagic fishes that are targeted by longline fisheries. We discuss the potential for exploiting differences in the sensory biology of these evolutionarily distinct groups to refine longline fishing techniques and reduce incidental bycatch of sea turtles without impacting the catch rates of targeted fish species. Based on the current evidence, differences in visual capabilities of sea turtles and pelagic fishes provide a promising avenue for development of a sensory-based deterrent.