A field experiment using acoustic alarms (pingers) to reduce harbour porpoise by-catch in bottom-set gillnets

Pingers were tested to reduce harbour porpoise (Phocoena phocoena) bycatch in bottom-set gillnets in the Swedish Skagerrak Sea. During the experiment, no harbour porpoise were caught in control or experimental gillnets, possibly as a result of a combination of factors including displacement of porpoise, high prey availability in other areas, or pingers acting as passive reflectors. Pingers did not affect the catch of target species, including cod and pollock.
Field Studies:

Location	Fishing gear	Reduction technique	Bycatch species	Effect on bycatch species	Catch	Effect on target catch	Type
Sweden	Gillnets	Acoustic pingers	Small Cetaceans (maximum length < 7.5 meters)	No bycatch in nets with or without pingers	Cod and pollock	Did not affect target catch	In the wild