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Summary: An excluder device, tested on a trawl net in a flume tank with dummy seals in New Zealand excluded dummy seals from the codend of the net. The modifications were trialed to address bycatch of Hookers sea lions and New Zealand fur seals.

Summary:

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.

Summary:

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.

Summary:

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. Thin twine monofilament nets (.4mm twine diameter, 90 mm mesh size) reduced bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to thick (.6mm twine diameter, 267 mm mesh size) monofilament nets. Barium sulphate nets had higher bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to traditional gillnets.

Summary:

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. Thin twine monofilament nets (.4mm twine diameter, 90 mm mesh size) reduced bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to thick (.6mm twine diameter, 267 mm mesh size) monofilament nets. Barium sulphate nets had higher bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to traditional gillnets.

Summary: A trap-net modification reduced seal-induced [Grey seal (Halichoerus grypus) and Ringed seal (Phoca hispida botnica)] catch and gear damage in the northern Baltic Sea trap-net fishery for salmon (Salmo salar) and whitefish (Coregonus lavaretus). Target catch remained the same or increased in four of five modified traps.

Summary:

Pot-gear modifications or sea lion exclusion devices (SLEDs) were tested in the Australian West Coast rock lobster (Panulirus cygnus) pot fishery to reduce bycatch of Australian sea lion (Neophoco cinerea) pups and juveniles. Although low levels of interactions in this preliminary study make testing the efficacy of the gear modification difficult, early tests indicate the SLEDs do not reduce rock lobster catch in shallow water. In deep water, redneck-batten and redneck-bolt pots reduced lobster catches but in fingerneck-bolt pots, there was no significant difference in catch from normal pots. Pot-gear modifications are mandatory in this fishery.

Summary:

Several designs of seal exclusion devices (SEDs) were tested to reduce bycatch of seals in the winter blue grenadier trawl fishery. A 'top-hatch' SED, or one with a top-mounted escape hatch, resulted in the lowest occurrence of seal bycatch than any other SED design or than nets without a SED. The SED prevented entry into the net codend where drownings occurred. They also successfully expelled seals and limited access into the net via the escape hatch. Cameras are needed to verify the results.

Summary:

AHDs with a source level of 179 dB re 1 µPa rms at 1 m were deployed during three consecutive fishing seasons. Fish catches in traps with AHDs were significantly higher than in the controls, while catch damage in the traps with AHDs was lower. However, towards the end of the fishing season catch damage increased in traps with AHDs.

Summary:

Bycatch of Australian sea lions in rock lobster and shark gillnet fisheries is a key threat to the species. This report outlines and assesses methods for mitigating bycatch in these fisheries in South Australia. Gear modification was considered in the rock lobster fishery and spatial closures in the shark gillnet fishery. Spikes of different heights were tested to deter sea lions from entering rock lobster pots. Entry success significantly decreased with spikes extending high up into the collar (70 mm + from base) compared to other treatment and control pots.