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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.

Field studies were conducted in the Patuxent River, Maryland (U.S.), to quantify the bycatch of cloth-funnel eel pots with small and large openings, and to test the effect of a prototype bycatch reduction device on bycatch and catch.  The bycatch reduction device consisted of a 77 mm PVC ring that was rigged around the narrow end of the flexible eel pot entrance and was designed to physically exclude terrapins (Malaclemys terrapin). Eel pots fitted with these bycatch reduction devices eliminated the bycatch of terrapin turtles but had no effect on the size or number of eels caught. These BRDs also did not increase pot handling time.

Tests were conducted aboard small (<10 m long) static net fishing vessels targeting monkfish (Lophius americanus) off the coast of Britain to determine the response of cetaceans (largely harbor porpoise, Phocoena phocoena and bottlenose dolphin, Tursiops truncatus) to pingers.  AQUAmark 100 pingers were positioned at 200 m intervals on the net and acoustic click detectors (C-PODs) were placed at the end of 1 km tiers of the net to determine the response of cetaceans to the pingers.  Only one harbour porpoise was incidentally caught during these trials and there was a significant reduction in the number of porpoise clicks recorded at nets with pingers compared to those without.  Additional tests were conducted to determine habituation. For these tests, modified pingers, active for alternate seven hour periods, were attached below click detectors at one site with strong tides and loud ambient noise and one at a quite site.  The results of this part of the study showed the pinger effect was stronger at the quiet site and that were was no habituation.  In addition, there was evidence of exclusion of porpoises following pinger use for as much as seven hours.

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.  

A modified longline system with a net sleeve and weight on the secondary vertical line was tested in the Chilean Patagonian toothfish (Dissostichus eleginoides) fishery. A net sleeve that deploys to cover the fish/hook when hauled and a weight were attached to the vertical hook line. The net sleeve significantly reduced depredation of fish by killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus). The weighted line also was able to reduce seabird bycatch deaths to zero.  

A modified longline system with a net sleeve and weight on the secondary vertical line was tested in the Chilean Patagonian toothfish (Dissostichus eleginoides) fishery. A net sleeve that deploys to cover the fish/hook when hauled and a weight were attached to the vertical hook line. The net sleeve significantly reduced depredation of fish by killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus). The weighted line also was able to reduce seabird bycatch deaths to zero.  

The Patagonian toothfish (Dissostichus eleginoides) longline fishery in the Southwest Atlantic suffers from depredation of fish by sperm whales (Physeter macrocephalus) and high bycatch rates of seabirds. This study assessed depredation and seabird bycatch using a modified longline with an "umbrella" net sleeve system with stones for faster sinking. The "umbrella-and-stones" system was effective for preventing bycatch and appeared to restrict depredation, but catches were significantly reduced.  

The Patagonian toothfish (Dissostichus eleginoides) longline fishery in the Southwest Atlantic suffers from depredation of fish by sperm whales (Physeter macrocephalus) and high bycatch rates of seabirds. This study assessed depredation and seabird bycatch using a modified longline with an "umbrella" net sleeve system with stones for faster sinking. The "umbrella-and-stones" system was effective for preventing bycatch and appeared to restrict depredation, but catches were significantly reduced.  

A new toothless dredge design called the "Newhaven" was tested in the Isle of Man queen scallop (Aequipecten opercularis) fishery, to determine its effect on both catch and bycatch.  This new dredge design caught significantly more queen scallops compared to the traditional tooth dredge. However, there was no significant difference between the abundance of bycatch between the two dredge designs.  Bycatch species composition between the two dredge types was relatively similar but the "Newhaven" dredge did catch a significant number of dogfish (Scyliorhinus canicula).