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Novel tools to reduce seabird bycatch in coastal gillnet fisheries

Acoustic pingers reduced the bycatch of the Common Murre (Uria aalge) in the Puget Sound salmon drift gillnet fishery, but they did not reduce bycatch of the rhinoceros auklet (Cerorhinca monocerata). Reduction of target species catch was not significant. White gillnet mesh panels in the upper portion of the net reduce the bycatch of seabirds (Common Murres and Rhinoceros Auklet) in the Puget Sound salmon drift gillnet fishery. Rhinoceros Auklet bycatch was only reduced in 50-mesh visual alert nets. The white mesh panels decreased salmon catch in 50-mesh but not in 20-mesh.

Incidental capture of sea turtles in shrimp trawls with and without TEDs in U.S. Atlantic and Gulf Waters

Turtle Excluder Devices reduce sea turtle bycatch in the Atlantic and Gulf of Mexico shrimp trawl fishery.

Technologies to reduce seal-fisheries interactions and mortalities

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.

Experiments in the Western Atlantic Northeast Distant Waters to Evaluate Sea Turtle Mitigation Measures in the Pelagic Longline Fishery. Report on Experiments Conducted in 2001-2003

Circle hooks significantly reduce loggerhead (Caretta caretta) and leatherback (Dermocheles coriacea) sea turtle bycatch in Atlantic longline fisheries. Swordfish catch decreased when circle hooks were baited with squid but increased when baited with mackerel. Tuna catch increased when circle hooks were baited with squid but decreased when baited with mackerel.

Experiment to Evaluate Gear Modification on Rates of Sea Turtle Bycatch in the Swordfish Longline Fishery in the Azores Phase 2

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.

Experiment to Evaluate Gear Modification on Rates of Sea Turtle Bycatch in the Swordfish Longline Fishery in the Azores Phase 3

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.

Experiment to Evaluate Gear Modification on Rates of Sea Turtle Bycatch in the Swordfish Longline Fishery in the Azores Phase 4

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.

Experiment to Evaluate Gear Modification on Rates of Sea Turtle Bycatch in the Swordfish Longline Fishery in the Azores

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.

Experiments in the Western Atlantic Northeast Distant Waters to Evaluate Sea Turtle Mitigation Measures in the Pelagic Longline Fishery. Report on Experiments Conducted in 2001

Blue-dyed bait does not significantly reduce loggerhead (Caretta caretta) and leatherback (Dermocheles coriacea)sea turtle captures in the western Atlantic longline fishery.

Nylon barium sulphate gillnet reduces porpoise and seabird mortality

Metal oxide nets containing barium sulphate (that increased their acoustic reflectivity and probably also their stiffness) reduced the bycatch of harbor porpoise (Phocoena phocoena) in an eastern Canada demersal gillnet fishery. No difference in catch of commercial fish species, including cod, pollock, haddock, and spiny dogfish, was observed between the nylon and barium sulphate nets. Metal oxide nets reduced the bycatch of greater shearwater (Puffinus gravis) in an eastern Canada demersal gillnet fishery, probably by increasing the visibility of the blue-dyed nets to the birds.

Target strength of a nylon monofilament and an acoustically enhanced gillnet: predictions of biosonar detection ranges

Metal oxide nets made from barium sulphate increased the detectability of gillnets by marine mammals when compared to nylon nets when approached at angles of incidence greater than normal incidence but less than 40 degrees. Hypothesized detection ranges indicate bottlenose dolphins (Tursiops truncatus) should be able to detect metal oxide nets in time to avoid entanglement, but harbor porpoise (Phocoena phocoena) may not be able to detect either net in time to avoid contact.

The composite square-mesh panel: a modification to codends for reducing unwanted bycatch and increasing catches of prawns throughout the New South Wales oceanic prawn-trawl fishery

Composite-panel codend netting decreased catch of non-target species, including commercially important whiting, while increasing catches of prawns in the NSW, Australia oceanic prawn-trawl fishery. Increases in retained octopus and red mullet and discarded eastern blue spot flathead (probably due to their large size) were observed.

Effectiveness of the Nordmore grate in the Gulf of Maine Northern shrimp fishery

A Nordmore sorting grid, which has been required in the Gulf of Maine Northern shrimp (Pandalus borealis) trawl fishery since 1992, was found to decrease bycatch of 8 groundfish species when observed tows before and after the grate requirement were compared. Catch rates of shrimp increased possibly due to higher catch rates of large shrimp.

A review of dolphin and porpoise bycatch issues in the Southwest of England

An excluder device, tested in the United Kingdom bass pair trawl fishery, did not reduce bycatch of common dolphins (Delphinus delphis).

Reduction of cetacean bycatch in pelagic trawls

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.

Analysis and mitigation of cetacean bycatch in UK fisheries

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.

Interactions between the Indian River Lagoon blue crab fishery and the bottlenose dolphin, Tursiops truncatus

Trap guards, made of bungee cords, reduced interactions between bottlenose dolphin (Tursiops truncatus) and the Indian River Lagoon blue crab (Callinectes sapidus) pot fishery.

Reduction of seal-induced catch and gear damage by modification of trap-net design: Design principles for a seal-safe trap net

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.

Reducing incidental mortality of seabirds with an underwater longline setting funnel

An underwater setting funnel, used in conjunction with a bird-scaring line, reduced bycatch of albatross and petrel seabirds in the demersal longline fishery for Patagonian toothfish (Dissostichus eleginoides) off of the sub-Antarctic South African Prince Edward Islands. Although fish rates were not compared between sets with and without the funnel, it is predicted fish catch would improve with the use of the funnels as fishing would be permitted during the day in addition to current nighttime fishing.

Effectiveness of four industry-developed bycatch reduction devices in Louisiana's inshore waters

Three of four bycatch reduction devices placed on shrimp (Penaeus aztecus and Penaeus setiferus) trawls in the Gulf of Mexico reduced bycatch of fish species but also reduced catch of shrimp. The fourth bycatch reduction device increased catch of shrimp and fish when compared with control nets.

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