The effect of acoustic alarms on the by-catch of harbour porpoises in the Danish North Sea gill net fishery

Larsen, F.
Journal/Publisher Name
IWC Scientific Committee
Volume (Issue #)
Page #s
Contact information
Department of Marine Fisheries
Danish Institute for Fisheries Research
Charlottenlund Castle
DK-2920 Charlottenlund, Denmark

Bottom set gillnets with pingers (LU-1, 8 signals, 145 dB, 300 ms, random signal intervals) attached were tested against standard nets and nets with dummy pingers (double blind) to determine if they could reduce the incidental capture of harbour porpoises. The proportion (number of nets with porpoises/number without) of harbour porpoise bycatch was reduced from 0.00229 and 0.00295 for nets with dummy pingers and no pingers respectively, to 0.00015 for nets with active pingers. The difference in bycatch rates between nets with active and dummy pingers was statistically significant but not between nets with dummy pingers and with no pingers.