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Low-cost solutions to cetacean bycatch in global gillnet fisheries
Per Berggren, Andrew J Temple, Joanna Alfaro-Shigueto and Jeffrey C. Mangel
International Whaling Commission
Gillnets are used in many small-scale fisheries around the world. Cetaceans often occur as bycatch in gillnets which threaten population health. Bycatch mitigation strategies that work for large commercial fisheries may not be workable in small-scale fisheries because they are costly. This project tested the effectiveness of a simple, low-cost bycatch reduction method known as glass bottle alarms in a small-scale drift gillnet fishery in Peru. The bottle alarms, made from a glass drink bottle with a bolt inside, produce a sound, similar to that of a commercial “pinger”, that should allow dolphins to more effectively detect a gillnet and avoid capture. The results suggest that glass bottle alarms do not significantly reduce bycatch of dolphins or turtles in gillnets. Further, the alarms did not affect the catch of target fish except for a reduction in the occurrence of shark catch events. Another potential low-cost technology, plastic bottle acoustic reflectors, will be tested in the coming months in the same fishery.