Novel tools to reduce seabird bycatch in coastal gillnet fisheries
Acoustic Harassment Devices were not found to be effective in deterring New Zealand fur seals (Arctocephalus forsteri) from mid-water trawls in the New Zealand hoki fishery. Sea Lion Escape Devices are undergoing testing in New Zealand˙s hoki trawl fishery (for fur seals) and the squid trawl fishery (for Hookers˙s sea lion). Preliminary results indicate squid and fish loss via the escape hatch was minimal; in the hoki fishery, fish loss was confined to fast swimming species, including jack mackerel and warehou.
Circle hooks (non-offset 16/0 and 18/0) did not significantly reduce the number of loggerhead sea turtles (Caretta caretta) caught in the Azores longline swordfish and blue shark fishery when compared with non-offset and offset 9/0 J hooks. Use of circle hooks decreased the rate of throat hooking in loggerhead sea turtles. Circle hooks (non-offset 16/0 and 18/0) caught significantly more blue sharks than J hooks in the Azores longline swordfish and blue shark fisheries.
There was no significant difference in the number of loggerhead sea turtles caught in the Azores longline swordfish and blue shark fishery between straight 16/0, offset 16/0, and offset 18/0 circle hooks. Circle hooks decreased the rate of throat hooking in loggerhead sea turtles caught in the Azores longline swordfish and blue shark fishery. Straight 16/0 circle hooks caught the most blue sharks in the Azores longline swordfish and blue shark fishery, followed by offset 18/0 circle hooks. Offset 16/0 circle hooks caught the fewest blue sharks.
Japanese tuna hook 3.6mm S/S caught significantly more loggerhead sea turtles than non-offset 16/0 and 18/0 circle hooks and caught more turtles in the throat than the circle hooks in the Azores longline swordfish and blue shark fishery. Non-offset 18/0 circle hooks caught fewer loggerhead sea turtles than non-offset 16/0 circle hooks in the Azores longline swordfish and blue shark fishery. There was no significant difference in the number of blue sharks caught on non-offset 16/0 and 18/0 circle hooks in the Azores longline swordfish and blue shark fishery.
Circle hooks (non-offset 16/0 and 18/0) caught significantly more blue sharks than J hooks in the Azores longline swordfish and blue shark fisheries.
Acoustic pingers placed around the mouth of a pair trawl net in the United Kingdom bass pair trawl fishery did not reduce common dolphin (Delphinus delphis) bycatch.
Acoustic pingers placed in the rear of a pair trawl net in the United Kingdom bass pair trawl fishery did not reduce bycatch of common dolphins (Delphinus delphis). Multi-monofilament net, placed in the North Sea and West of Scotland gillnet fisheries, had no significant impact on harbour porpoise (Phocoena phocoena) bycatch when compared to traditional monofilament net.