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The authors conducted an extensive literature review to determine if Sea Lion Excluder Devices (SLEDs) allow sea lions (Phocarctos hookeri) to escape from trawl nets and if they subsequently survived. In addition, the literature was reviewed to determine if head trauma was likely when sea lions come into contact with stainless steel SLED grids. According to the literature, SLEDs are effective in reducing sea lion bycatch in trawl nets and resulted in a reduction of observed sea lion mortalities. In addition, the literature indicates that increased head trauma, due to contact with the SLED grids, is unlikely. 

Although effective in trials with captive loggerhead (Caretta caretta) and Kemp's ridley (Lepiochelys kempii) sea turtles, blue-dyed bait is not effective in reducing olive ridley (Lepidochelys olivacea) and green sea turtle (Chelonia mydas) bycatch in longline fisheries in Costa Rica.

18/0 circle hooks when compared with J hooks significantly reduce loggerhead (Caretta caretta) and leatherback (Dermocheles coriacea) sea turtle bycatch in Atlantic longline fisheries for pelagic swordfish (Xiphias gladius). Circle hooks also reduced the rate of hook ingestion by loggerhead sea turtles. The combination of circle hooks and mackerel (Scomber scombrus) bait was the most effective in reducing sea turtle bycatch and had no negative effect on swordfish catch. Loggerhead sea turtle (Caretta caretta) bycatch in the Atlantic longline fishery increased with an increase in total soak time. Soak time was insignificant for swordfish but it was significant for bigeye tuna (Thunnus obesus).

Circle hooks significantly reduce loggerhead (Caretta caretta) and leatherback (Dermocheles coriacea) sea turtle bycatch in Atlantic longline fisheries. Swordfish (Xiphias gladius) catch decreased when circle hooks were baited with squid but increased when baited with mackerel. Tuna catch increased when circle hooks were baited with squid but decreased when baited with mackerel.

There was no significant difference in the number of loggerhead sea turtles (Caretta caretta) caught in the Azores (Portugal) longline swordfish (Xiphias gladius) and blue shark (Prionace glauca) fishery between straight 16/0, offset 16/0, and offset 18/0 circle hooks. Circle hooks decreased the rate of throat hooking in loggerhead sea turtles (Caretta caretta) caught in the Azores longline swordfish and blue shark fishery. Straight 16/0 circle hooks caught the most blue sharks in the Azores longline swordfish and blue shark fishery, followed by offset 18/0 circle hooks. Offset 16/0 circle hooks caught the fewest blue sharks.

A Japanese tuna hook 3.6mm S/S caught significantly more loggerhead sea turtles (Caretta caretta) than non-offset 16/0 and 18/0 circle hooks and caught more turtles in the throat than the circle hooks in the Azores (Portugal) longline swordfish (Xiphias gladius) and blue shark (Prionace glauca) fishery. Non-offset 18/0 circle hooks caught fewer loggerhead sea turtles (Caretta caretta) than non-offset 16/0 circle hooks in the Azores longline swordfish and blue shark fishery. There was no significant difference in the number of blue sharks caught on non-offset 16/0 and 18/0 circle hooks in the Azores longline swordfish and blue shark fishery.

Rare earth metals (made of cerium mischmetal) were compared with control treatments of standard circle hooks and inert steel above circle hooks on longline fishing gear to determine if bycatch reduction of spiny dogfish (Squalus acanthias) could be achieved. Results indicated a slight reduction in dogfish bycatch and a greater reduction in catch of longnose skate (Caliraja rhina) on hooks with mischmetal. Problems for using mischmetal commercially include its expense, hazardous nature, and rapid hydrolysis in seawater.

Trials to assess the behavioral response of free-ranging bottlenose dolphins (Tursiops truncatus) to continuous and responsive pingers were conducted. In boat-based trials both types of pingers affected dolphin behavior, while in static trials, the detection of dolphin vocalizations was significantly lower in the presence of active continuous pingers.

The use of circle hooks (16/0) instead of J hooks (size 2) on pelagic longline gear, reduced the incidental capture of immature loggerhead sea turtles (Caretta caretta) and did not affect the catch rates or fish size of the target species (primarily swordfish (Xiphias gladius) and tuna (Thunnus spp.)). There was also a significant difference in hook location between the two hooks, with more J hooks being swallowed.

The effect of circle hooks and J-style hooks on the catch composition, catch rates, hooking location and status of release of target and bycatch species were compared on pelagic longline vessels.  There were significant differences in catch rates between the two hook types for bigeye tuna, which had higher catch rates on circle hooks and sailfish (Istiophorus spp.), pelagic stingrays (Pteroplatytrygon violacea), and leatherback sea turtles (Dermochelys coriacea), which had higher catch rates on J-style hooks. Survival of bigeye (Thunnus obesus) and yellowfin tunas (Thunnus albacares) was significantly higher when circle hooks were used, and bigeye and yellowfin tunas, swordfish (Xiphias gladius) and sailfish had significantly higher external hookings when circle hooks were used. The results suggests using 18/0 circle hooks with a zero degree offset could increase the survival of bycatch species while having minimal effects on the catches of target species.