Reducing incidental mortality of franciscana dolphin pontoporia blainvilei with acoustic warning devices attached to fishing nets
BORDINO, P.; KRAUS, S; ALBAREDA, D.; FAZIO, A.; PALMERIO, A.; MENDEZ, M.; BOTTA, S.
MARINE MAMMAL SCIENCE
WILEY-BLACKWELL PUBLISHING, INC
Lugar: Londres; Año: 2002 vol. 18 p. 833 - 842
We conducted a double blind experiment in an artisanal gillnet fishery in Argentina to determine the effectiveness of acoustic deterrents (pingers) at reducing bycatch of the Franciscana dolphin (Pontoporia blainvillei). The fishery was conducted by small inflatable and fiberglass vessels operating between 0.5 and 7 km from the coast. Each vessel carried an independent observer who was rotated from vessel to vessel throughout the course of the experiment. Information on the number of dolphins captured, geographic position, depth, configuration of fishing gear, soak time, biomass of fish caught, and sea lion predation in a string/net producing any damage was recorded. Equivalent numbers of active and silent pingers were used during the experiment. A total of 45 dolphins were caught in the silent nets, and seven were caught in the active pinger nets, demonstrating a highly significant reduction in bycatch for this species. However, sea-lions (Otaria flavescens) damaged the fish in active pinger nets significantly more than silent nets, and the damage increased over the course of the experiment. Although pingers show promise as a management tool for this species, pinniped depredation suggests that higher pinger frequencies will be needed to avoid a ´dinner bell´ effect.