The expansion of the eastern tropical Pacific (ETP) tuna purse-seine fleet from the 1960's to the present has involved a long history of dolphin mortality incidental to fishing operations (NRC 1992, Joseph 1994). These dolphin deaths led to an escalating interaction between fishing interests, government, and environmental organizations. Amendments to the Marine Mammal Protection Act of 1972 (Section 110(a) November 23, 1988) directed the National Marine Fisheries Service (NMFS) to investigate methods to locate and capture large yellowfin tuna, Thunnus albacares, that do not involve encircling dolphins with a net. Successful introduction of such methods would help reduce, if not eliminate, the incidental mortality of dolphins which occurs in the ETP tuna purse-seine fishery, while maintaining a viable fishery resource. Congress further directed the Secretary of Commerce to arrange for an independent review of potential alternative fishing methods to be conducted by the National Research Council (NRC 1992). In response, the NMFS formed the Alternative Gear Task at the Southwest Fisheries Science Center in La Jolla, California during the second half of 1989.
A series of annual workshops were conducted during 1989-1991 focused on methods to reduce dolphin mortality (Rodriguez et al. 1990; Vlymen 1991; DeMaster et al. 1992) and the National research Council published their report of the fishery (NRC 1992). From these workshops, and the NRC effort, a strategic plan for Dolphin-Safe Research was developed (DeMaster 1992) and a report on the research efforts through July 1991 prepared (Young and Armstrong 1992).
The dolphin-safe researchers began another series of ETP-related studies in 1992, focused on developing and evaluating methods of capturing yellowfin tuna which do not involve dolphins. Investigations on the potential for technology applications to enhance efficiency in commercial fisheries, reduce the catch of non-targeted species, and provide new tools for fishery assessments in support of the NMFS strategic goals to build sustainable fisheries and recover protected species have been completed. Studies on the potential use of airborne lidar (LIght Detection And Ranging) systems began in 1991, and studies on low-frequency acoustic systems to detect fish schools at ranges much greater than currently possible were initiated during 1995. In addition to their use as an alternative to fishing on dolphins, these systems have potential to increase the efficiency of the fishing operations by locating fish schools not detectable by customary visual means, and as a fishery-independent tool to conduct population assessments on pelagic fish. They also have potential to adversely impact marine animals.