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The presence of permanent magnets on hook and line and inshore longline gear was tested for its ability to reduce the bycatch of sharks and rays.  Neodymium-iron-boron magnets were affixed to hook and line gear and barium-ferrite magnets were attached to longline gear.  Both types of fishing gear showed species specific responses but overall elasmobranch capture was significantly reduced when magnets were used. In the hook and line fishery catches of the Atlantic sharpnose shark and smooth dogfish were both significantly reduced when magnets were used but catches of spiny dogfish and clearnose skate were not.  Similarly, in the longline fishery blacktip sharks and southern stingray catch rates were reduced but sandbar shark catch rates were not when magnets were used.  There were no differences in the catch rates of several fish species, including Atlantic croaker, oyster toadfish, black sea bass and bluefish when magnets were used.  

At-sea and on-shore trials were conducted to test the safety and effectiveness of an alternative line weight called the Safe Lead.  This new line weight is designed to reduce danger to the crew in the event of a bite-off by sliding down or off the line.  At-sea trials were conducted in South Africa and indicated that dangerous fly-backs, a result of a bite-off, were reduced when the Safe Lead was used. During these trials, only 4.2% of Safe Lead fly-backs reached the fishing vessel, compared to 73.3% with traditional leaded swivels.  On-shore trials indicated that the degree of slippage of the Safe Lead off the line was dependent on the distance from the Safe Lead to the hook and the tension on the line. When the Safe Lead was placed within 2m of the hook, it slid off the line under all four tension treatments.  Safe Leads appear to be both a cost effective and operationally simple alternative to traditional leaded swivels.

The presence of permanent magnets on hook and line and inshore longline gear was tested for its ability to reduce the bycatch of sharks and rays.  Neodymium-iron-boron magnets were affixed to hook and line gear and barium-ferrite magnets were attached to longline gear.  Both types of fishing gear showed species specific responses but overall elasmobranch capture was significantly reduced when magnets were used. In the hook and line fishery catches of the Atlantic sharpnose shark and smooth dogfish were both significantly reduced when magnets were used but catches of spiny dogfish and clearnose skate were not.  Similarly, in the longline fishery blacktip sharks and southern stingray catch rates were reduced but sandbar shark catch rates were not when magnets were used.  There were no differences in the catch rates of several fish species, including Atlantic croaker, oyster toadfish, black sea bass and bluefish when magnets were used.  

Two new branch weighting techniques were tested aboard Australian pelagic longline vessels to determine their effect on catch rates of both target and non-target species and their potential use for seabird mitigation.  The two new branch lines included one with a 120 g lead weight < or equal to 2 m from the hook or a branch line with a 40 g lead weight placed at the hook.  There were no significant differences in catch rates for either the main target (yellowfin tuna, albacore tuna, bigeye tuna, swordfish and mahi mahi) or non-target species (sharks) between the industry standard branch line and either of the new ones.  However, the new branch line with the 40 g weight sank more quickly than the industry standard, improved crew safety and reduced the amount of time spent constructing gear. Therefore this option may have the potential to reduce seabird interactions without affecting catch rates of target species.

Odontocete (i.e. toothed whale) interaction with longline fisheries is a global phenomenon that threatens the status of some populations and the economic viability of longline fisheries. This review paper summarizes the trend and geographical extent of interactions, the potential impact on odontocetes and fisheries, and describes potential acoustic and physical mitigation solutions. 

Two devices were designed to prevent odontocetes from depredating caught fish and putting themselves at-risk of becoming bycatch. One device used physical deterrence by shouding the fish with a barrier and the other used psychological deterrence by utilizing prior negative experiences of temporary entanglement in fishing gear. Both devices fit on a branchline at a distance from the hook and descend towards a caught fish using a line tension trigger mechanism. All interactions occurred on control branchlines that were not fitted with a deterrent device, suggesting the potential of this technology to deter depredating odontocetes. The impact on fish catch rates, size, and survival was negligible. 

An acoustic device designed to deter false killer whales from approaching longlines by reducing the whales' echolocation performance capabilities was tested on a trained false killer whale. The device, Longline Saver, produced a series of complex, broadband signals (1-250 kHz) at high intensity levels (up to 182 dB). The whale was asked to detect a target in the presense or abscence of the acoustic device. Initially, the device reduced the whale's echolocation performace to chance levels, however subsequent trials demonstrated improvement in echolocation.  

A study was conducted aboard the Cornish inshore gillnet fishery to determine if pingers could reduce porpoise and bottlenose dolphin bycatch, whether habituation to the pingers would reduce their effectiveness and how quickly porpoises and dolphins recolonise a pingered site after their removal. Vessels were equipped with passive acoustic monitoring systems that can recognize and log each animals click and AQUAmark 100 pingers were spaced 200 m apart on the nets.  Control nets with no pingers were also used.  There was a significant difference in the number of porpoise clicks between nets with and without pingers.  There was no significant difference in the proportion of loud clicks logged when pingers were active and so the extent of displacement by pingers cannot be determined. In addition, there was no evidence of habituation to the pingers.  It appears that porpoises take at least 7 hours to recolonise a pingered site. There were too few encounters with dolphins to determine the ability of pingers to reduce their bycatch or to determine how long recolonization will take.

This investigation details an unusual encounter with a lunge-feeding minke whale with fresh entanglement-like injuries to its head and ventral pouch.  It also discusses results from a short-term comparative study that tested whether the whale fed differently than five uninjured minke whales feeding in the same area.  Collectively, this study: 1) quantifies how much a rope-like injury can restrict the expansion of a minke's ventral pouch while feeding, 2) provides the first minke whale lunge-feeding velocities from a photogrammetric method using digital video, and 3) describes a new lunge-feeding aerial maneuver for minke whales that is possibly associated with the injury.