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Summary:

Bycatch can be reduced in Queensland’s scallop (Ylistrum balloti) and deepwater king prawn (Melicertus plebejus) fisheries by 77% and 29% respectively by using square mesh codends in conjunction with efficient turtle excluder devices (TEDs), with no loss of the target species catch. Further consultation with approximately 40% of the Queensland East Coast Trawl Fishery, as well as netmakers, importers, and manufacturers resulted in improvements to both the methods and materials of the square mesh codend construction. Additional at-sea trials demonstrated that marketable prawn catch rates could be maintained while reducing bycatch by 31.2%. Catch of undersized and non-marketable prawns was also reduced. 

Summary:

Bycatch can be reduced in Queensland’s scallop (Ylistrum balloti) and deepwater king prawn (Melicertus plebejus) fisheries by 77% and 29% respectively by using square mesh codends in conjunction with efficient turtle excluder devices (TEDs), with no loss of the target species catch. Further consultation with approximately 40% of the Queensland East Coast Trawl Fishery, as well as netmakers, importers, and manufacturers resulted in improvements to both the methods and materials of the square mesh codend construction. Additional at-sea trials demonstrated that marketable prawn catch rates could be maintained while reducing bycatch by 31.2%. Catch of undersized and non-marketable prawns was also reduced. 

Summary: A warp cable modification (plastic cone attached to each warp cable) reduced seabird bycatch in the high-sea Argentine hake (Merluccius hubbsi) trawl fishery. The two most abundantly captured seabirds prior to the attachment of plastic cones were the Kelp gull (Larus dominicanus) and the Black-browed albatross (Thalassarche melanophrys).

Summary: School shark (Galeorhinus galeus) liver oil dripped behind fishing vessels in the northern New Zealand snapper (Pagrus auratus) longline fishery reduced seabird numbers and dives on baits when compared to canola oil and seawater control treatments. The shark liver oil did not affect the number of target snapper, gurnard (Chelidonicthys kumu), kaha-wai (Arripis trutta), or trevally (Pseudocaranx dentex) caught.

Summary: Five codend designs and four behavioral-type bycatch reduction devices were tested to reduce fish bycatch in the broad squid (Photololigo etheridgei) and bottle squid (Loliolus noctiluca) trawl fishery in New South Wales, Australia. Reducing posterior circumference, increasing mesh size, and changing to diamond-shaped mesh did not improve trawl selectivity. A square-mesh codend did improve selectivity by reducing fish bycatch by 71% without reducing squid catch.

Summary: Three seabird bycatch mitigation measures, tori lines, warp scarer, and Brady baffler, were tested on trawlers and compared with a control treatment of no mitigation measure. Each mitigation measure reduced seabird mortalities; however, the tori lines, followed by the warp scarer, were much more effective at reducing seabird contact with fishing gear than the Brady baffler.

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: The requirement, in 2003, that trawl vessels fishing for ocean shrimp use bycatch reduction devices (BRDs) has reduced fish bycatch by between 66% and 88% from historical (pre-BRD) levels. Data collected from a trawl experiment testing a rigid-grate BRD with 19-mm bar spacing suggest that bycatch in the ocean shrimp fishery can be reduced further, perhaps below 5% of total catch.

Summary: To reduce turtle interactions, regulations for the Hawaii-based longline swordfish fishery required vessels to switch from using a J-shaped hook with squid bait to a wider circle-shaped hook with fish bait. Analyses of observer data showed that, following the introduction of the regulations, significant and large reductions in sea turtle and shark capture rates occurred without compromising target species catches. There was also a highly significant reduction in the proportion of turtles that swallowed hooks and a highly significant increase in the proportion of caught turtles that were released after removal of all terminal tackle. Research suggests that turtles aggregate at foraging grounds and that instituting methods to avoid real-time turtle bycatch hotspots may further reduce turtle interactions.

Summary: To reduce turtle interactions, regulations for the Hawaii-based longline swordfish fishery required vessels to switch from using a J-shaped hook with squid bait to a wider circle-shaped hook with fish bait. Analyses of observer data showed that, following the introduction of the regulations, significant and large reductions in sea turtle and shark capture rates occurred without compromising target species catches. There was also a highly significant reduction in the proportion of turtles that swallowed hooks and a highly significant increase in the proportion of caught turtles that were released after removal of all terminal tackle. Research suggests that turtles aggregate at foraging grounds and that instituting methods to avoid real-time turtle bycatch hotspots may further reduce turtle interactions.