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KEY WORDS: albatross, bycatch, Hawaii, longline fishery, seabird.Capture in longline fisheries is a critical threat to most albatross and large petrel species. 1-3 Blackfooted Phoebastria nigripes and Laysan P. immutabilis albatrosses are the predominant seabird species incidentally caught in Hawaii longline fisheries. This study reports results of a trial in the Hawaii pelagic longline tuna and swordfish fisheries comparing four experimental treatments' seabird capture rates and commercial viability. Two research fishing trips were conducted between 1 April and 17 May 2003 on a Hawaii-based pelagic longline vessel, at traditional fishing grounds south of the Northwestern Hawaiian Islands, between 21°41′N and 25°08′N, 173°58′W and 167°43′W.Two of the treatments employed were setting branch lines through 9 m and 6.5 m long underwater setting chutes, which release baited hooks beneath the sea surface, in an attempt to prevent diving seabirds from reaching them. The design of the underwater setting chute, illustrated in Molloy et al., 4 is similar to that used in this present trial. When setting with the 9 m and 6.5 m chutes on the research vessel, 5.4 m and 2.9 m of the chute's shaft was underwater, respectively.A third treatment, called side-setting, entailed setting from the side of the vessel, with other gear design the same as conventional approaches when setting from the stern. The crew throwing baited hooks was 8 m forward from the port-stern corner. Baited hooks were thrown forward, close to the side of the vessel's hull, to protect baits from seabirds. A bird curtain was used, 4.9 m forward from the portstern corner, when side-setting to increase the effectiveness of this mitigation method by preventing birds from establishing a flight path along the side of the boat where baited hooks were being deployed. The hypothesis is that when side-setting, baited hooks will be set close to the side of the vessel hull where seabirds will be unable or unwilling to pursue the hooks. By the time the stern passes the hooks, the hooks will have sunk to a depth where seabirds cannot locate them or cannot dive.A fourth treatment was blue-dyed bait. Bait was completely thawed and dyed blue by soaking in a large tub with dissolved blue food coloring (Virginia Dare FD & C Blue no. 1) powder at a concentration of 4 g/L of water for 1-4 h to achieve regulatory-required darkness. The hypothesis is that dyed bait is difficult for birds to detect because it reduces the contrast between bait and sea color.Research on the efficacy of blue-dyed bait and underwater setting chutes for pelagic longline fisheries at reducing seabird bycatch has been conducted previously. 5,6-10 This present study is the first assessment of the effectiveness of side-setting at reducing seabird capture.Setting occurred only during daylight to enable observations of seabird interactions with fishing gear. Both tuna and swordfish gear used 60 g swivels attached within 1 m of the hook, a weighting design selected by the Hawaii Longline Association. Gilman et a...

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Marine aquaculture of the salmonids atlantic salmon (Salmo salar) and rainbow trout (Salmo gairdnerz) is a rapidly growing industry in Tasmania. There is considerable damage to the fish on these farms by avian and mammalian predators. The mode by which these predators attack the fish on the farms allows for practical methods to reduce the loss of fi sh. Physically excluding predators from the fish is ultimaLely the only way to prevent this loss entirely. A total of six predators that interact with the farms are described and the necessity for the protection methods ro be incorporated into the design of the farms prior to farm development is emphasised.

Fishery-cetacean interactions, including those with longline gear, give rise to economic, ecological and social concerns. This paper reviews problems resulting from cetacean-longline interactions, considers potential strategies to reduce interactions and identifies research priorities and approaches. Depredation by cetaceans (removal and damage of hooked fish and bait from fishing gear) and damage and loss of fishing gear create economic problems; however, the magnitude of this problem is poorly understood. There is also insufficient information to determine whether there are population-level effects resulting from injury and mortality of cetaceans (from incidental entanglement and hooking and from deliberate actions to discourage depredation). Fishery-cetacean interactions may also: change cetacean foraging behaviour and distribution; increase fishing effort to make up for fish taken from gear by cetaceans; and create errors in fish stock assessments that do not account for cetacean depredation. Negative public perceptions of longline fishing can result from news of incidental and deliberate injury and mortality of cetaceans associated with longlining. Information on how to reduce cetacean interactions with longline gear is also limited, as is the understanding of the mechanisms responsible for them. Strategies already employed in some fleets include refraining from setting or cutting sets short when problematic species of cetaceans are observed and fleet coordination of daily fishing times and positions. Many fishermen perceive depredation as an inevitable part of fishing. This paper discusses a number of other possible cetacean avoidance strategies that warrant consideration, including: (1) fleet communication to enable vessels to avoid temporally and spatially unpredictable and sporadic hotspots of aggregations of cetaceans; (2) underwater acoustic masking devices to conceal the sound of the vessel, gear, and setting and hauling activities; (3) quieter vessels to reduce cetaceans’ ability to target longline vessels; (4) encasement of caught fish to reduce cetacean access to or interest in the catch; (5) use of bait or gear with an unpleasant smell or taste to reduce the attractiveness of gear, bait and catch to cetaceans; (6) use of pre-recorded fishing vessel sounds played from stations throughout a fleet’s fishing grounds to distract cetaceans from actual fishing vessels; (7) use of acoustic devices to mask returning cetacean echolocation signals; and (8) use of tethered sonobuoys to track cetaceans and enable fleet avoidance. Vessels with relatively low cetacean interaction rates should be examined for design and operational differences from vessels with high interaction rates, possibly allowing identification of effective avoidance methods. There is a need for experimentation in individual longline fisheries over several seasons to assess fisheryspecific efficacy and commercial viability of cetacean avoidance strategies. This is necessary as different cetacean species likely respond differently to an avoidance method and cetaceans may habituate to an avoidance strategy, especially in fisheries interacting with resident cetaceans.