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Experiments were conducted aboard Korean pelagic longline vessels to determine if there were differences in the catch rates of target (tuna and billfish) and bycatch (sharks and other bony fish) species between 3 types of hooks; 4.0 traditional tuna hook (J-4), size 15 circle hook (C15) and size 18 circle hook (C18).  Within the target group significant differences between catch rates were only found between the J-4 and C18 hooks.  In the bycatch species group, significant differences were found between J4 and C15 and between J4 and C18.  Overall, the large circle hook (C18) had the lowest catch rates for tunas and other fish, while small circle hooks (C15) had the lowest catch rates for billfish and sharks.  Any differences in the length of fish caught by the individual hooks were minimal.

Experiments were conducted aboard Korean pelagic longline vessels to determine if there were differences in the catch rates of target (tuna and billfish) and bycatch (sharks and other bony fish) species between 3 types of hooks; 4.0 traditional tuna hook (J-4), size 15 circle hook (C15) and size 18 circle hook (C18).  Within the target group significant differences between catch rates were only found between the J-4 and C18 hooks.  In the bycatch species group, significant differences were found between J4 and C15 and between J4 and C18.  Overall, the large circle hook (C18) had the lowest catch rates for tunas and other fish, while small circle hooks (C15) had the lowest catch rates for billfish and sharks.  Any differences in the length of fish caught by the individual hooks were minimal.

An experimental release panel was installed in purse seine nets to determine their ability to release both silky sharks (Carcharhinus falciformis) and non-target finfish.  The release panels (5.5 m wide, extending down from the corkline for 11 m) were installed in a portion of the net that forms a "pocket" toward the end of net retrieval.  Dive surveys previously reported that silky sharks tend to segregate and collect in this section of the net. The release panel was tested during seven purse seine sets, but only two silky sharks (out of 105) exited through this panel. In net observations indicated that sharks and other non-target finfish did not appear to recognize the opening as an escape route out of the net. Despite this initial failure of the release panel, the authors feel refinement of the panel and additional testing is still warranted.

An experimental release panel was installed in purse seine nets to determine their ability to release both silky sharks (Carcharhinus falciformis) and non-target finfish.  The release panels (5.5 m wide, extending down from the corkline for 11 m) were installed in a portion of the net that forms a "pocket" toward the end of net retrieval.  Dive surveys previously reported that silky sharks tend to segregate and collect in this section of the net. The release panel was tested during seven purse seine sets, but only two silky sharks (out of 105) exited through this panel. In net observations indicated that sharks and other non-target finfish did not appear to recognize the opening as an escape route out of the net. Despite this initial failure of the release panel, the authors feel refinement of the panel and additional testing is still warranted.

A structured literature review of 103 papers was conducted to characterize trends in shark bycatch research.  Gear modifications, such as hook size/type and net size, were the most commonly evaluated technique to reduce shark bycatch.  Early studies tended to focus on trawl fisheries while more current studies focus on longline fisheries, particularly tuna fisheries. Overall, longline fishery studies made up the majority (44.6%) of published papers and typically were aimed at reducing bycatch.  Later studies also tended to explore potential solutions to bycatch issues.  In terms of trawl fisheries, net size and mesh design were most commonly suggested to reduce shark bycatch, while in longline fisheries, hooks size and type were the most common options suggested. The majority of published papers (40%) focus on the North Atlantic Ocean followed by the North Pacific Ocean (14.4%).  The lack of information on post-release survivorship of sharks made it difficult for the authors to quantify the true amount of bycatch or to recommend handling techniques to fishermen.

Research was conducted in the western North Atlantic Ocean to determine what effect changes to the hook design and bait type would have on pelagic longline  bycatch.  Three types of hooks, 18/0 and 20/0 circle hooks and 10/0 Japanese tuna hooks with squid and mackerel bait were tested against the standard 9/0 J-hook with squid bait.  Circle hooks and mackerel bait, individually, significantly reduced loggerhead (Caretta caretta) and leatherback sea turtle (Dermochelys coriacea) bycatch.  Combined, 18/0 circle hooks and mackerel bait reduced loggerhead sea turtle bycatch, while swordfish (Xiphias gladius, a targeted species) catch by weight increased. Combined 18/0 circle hooks with squid bait significantly decreased swordfish catch rates but significantly increased blue shark (Prionace glauca), bluefin tuna (Thunnus thynnus) and albacore tuna (Thunnus alalunga) catch rates.  Blue shark, bigeye (Thunnus obesus) and albacore tuna catch rates were always reduced when mackerel bait was used but porbeagle (Lamna nasus) and shortfin mako shark (Isurus oxyrinchus) catch rates increased with this bait type.

Longlines with baited hooks affixed with a block of metal alloy (Nd/Pr) were tested against hooks with a lead weight attached (control), to determine their ability to repel sharks. Two experiments were conducted in Hawaiian waters (U.S.), one in the Southern California Bight (SCB) and and one in the Eastern Tropical Pacific off the coast of Ecuador.  Significant differences were only found for juvenile hammerhead sharks (Sphyrna lewini) targeted in one of the Hawaiian experiments. No significant differences were found during experiments targeting sandbar (Carcharhinus plumbeus) and tiger sharks (Galeocerdo cuvier) during the second Hawaiian experiment, for shortfin mako (Isurus oxyrinchus) or blue sharks (Prionace glauca) in the SCB, or for pelagic thresher (Alopias pelagicus) and blue sharks off the coast of Ecuador.  

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 (Rhizoprionodon terraenovae) and smooth dogfish (Mustelus canis) were both significantly reduced when magnets were used but catches of spiny dogfish (Squalus acanthias) and clearnose skate (Rostroraja eglanteria) were not.  Similarly, in the longline fishery, blacktip sharks (Carcharhinus limbatus) and southern stingray (Hypanus americanus) catch rates were reduced but sandbar shark (Carcharhinus plumbeus) catch rates were not when magnets were used. There were no differences in the catch rates of several fish species, including Atlantic croaker (Micropogonias undulatus), oyster toadfish (Opsanus tau), black sea bass (Centropristis striata) and bluefish (Pomatomus saltatrix) when magnets were used.  

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 (Rhizoprionodon terraenovae) and smooth dogfish (Mustelus canis) were both significantly reduced when magnets were used but catches of spiny dogfish (Squalus acanthias) and clearnose skate (Rostroraja eglanteria) were not.  Similarly, in the longline fishery, blacktip sharks (Carcharhinus limbatus) and southern stingray (Hypanus americanus) catch rates were reduced but sandbar shark (Carcharhinus plumbeus) catch rates were not when magnets were used. There were no differences in the catch rates of several fish species, including Atlantic croaker (Micropogonias undulatus), oyster toadfish (Opsanus tau), black sea bass (Centropristis striata) and bluefish (Pomatomus saltatrix) when magnets were used.