2006 Sea Turtle and Pelagic Fish Sensory Physiology Workshop

The five species of sea turtles found in the Pacific Ocean are either listed under the U.S. Endangered Species Act of 1973 as threatened (loggerhead, Caretta caretta; green, Chelonia mydas; and olive ridley, Lepidochelys olivacea) or as endangered (leatherback, Dermochelys coriacea and hawksbill, Eretmochelys imbricata). Many Pacific nesting populations of these turtles have seen a recent decline. These declines may be based on multiple factors, including direct mortality as a result of harvesting of adults and juveniles, poaching of eggs on nesting beaches, natural mortality by disease and predation, destruction and degradation of suitable habitat for nesting beaches, as well as the incidental capture of sea turtles in fishing gear.

There is a growing concern that interactions with fisheries, specifically longline fishing operations, negatively affect sea turtle populations worldwide. The level of sea turtle bycatch in pelagic longline fisheries is of great concern to environmentalists, the fishing industry, and fisheries managers alike. In the United States, recent protective measures have resulted in legally mandated gear modifications (e.g., large circle hooks) as well as time-and area fisheries closures in both the Pacific and Atlantic Oceans. However, for a number of reasons, such measure may not be practical in all fisheries, and thus other methods of reducing sea turtle bycatch should also be considered.

Factors that attract sea turtles and target fish species to longline gear and bait are not well understood, but numerous sensory cues may be involved. In 2001, NOAA Fisheries scientists created the Sensory Biology Working Group and launched a multidisciplinary, interagency research program to investigate the visual, auditory, and chemosensory abilities of sea turtles and pelagic fishes. The purpose of the research was to identify differences between turtles and pelagic fish species that may be used to develop gear and bait attractive to fish but unattractive to sea turtles or undetectable by them. The primary objective of the research is to develop techniques and/or commercially viable devices that eliminate or substantially reduce interactions of sea turtles with longline fishing gear while not reducing catch rates of the targeted fish species to unacceptable levels.

Research projects have been underway since 2001, supported by funding from the Pacific Islands Fisheries Science Center (PIFSC), NOAA Fisheries, in Honolulu, Hawaii. Because of the complexity of the research, projects have necessarily involved a large and diverse team of scientists. Collaborating scientists have held three meetings prior to the 2006 meeting to discuss research progress.

This report summarizes findings reported by collaborating scientists at the 4th Sea Turtle and Pelagic Fish Sensory Physiology Workshop hosted by the Virginia Institute of Marine Sciences Eastern Shore Laboratory in Wachapregue, Virginia during September 12-13, 2006. Participants of this workshop included NOAA fisheries biologists, researchers from U.S. and foreign universities, and consultants from private companies. A list of participants and their affiliations is included at the end of this report.