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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, pelagic stingrays, and leatherback sea turtles, which had higher catch rates on J-style hooks.  Survival of bigeye and yellowfin tunas was significantly higher when circle hooks were used and bigeye and yellowfin tunas, swordfish 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.

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, pelagic stingrays, and leatherback sea turtles, which had higher catch rates on J-style hooks.  Survival of bigeye and yellowfin tunas was significantly higher when circle hooks were used and bigeye and yellowfin tunas, swordfish 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.

The type (circle 18/0 0 degree offset and J-style 9/0 10 degree offset) and position of hooks in the water column were tested to determine the effects on catch rates and mortality of elasmobranchs.  Tests were conducted aboard pelagic and bottom longline vessels. CPUEs for blue, silky and oceanic whitetip sharks were significantly higher with circle hooks than with J-style hooks. Silky, blue and oceanic whitetip sharks had a significantly higher mortality at haulback with J-style hooks.  Significant differences in hooking location between the two hook types was found for night, blue, silky and oceanic whitetip sharks. These sharks were more commonly hooked externally vs internally.  No significant differences between hook types was found for the CPUE's on bottom longlines.  Significantly more blacknose were alive at haulback when circle hooks were used on bottom longlines. Bottom longlines were also used to test for differences in CPUE by fishing depth.  Demersal hooks had significantly higher CPUE's than those suspended in the water column for blacknose and nurse sharks and southern stingrays.

The type (circle 18/0 0 degree offset and J-style 9/0 10 degree offset) and position of hooks in the water column were tested to determine the effects on catch rates and mortality of elasmobranchs.  Tests were conducted aboard pelagic and bottom longline vessels. CPUEs for blue, silky and oceanic whitetip sharks were significantly higher with circle hooks than with J-style hooks. Silky, blue and oceanic whitetip sharks had a significantly higher mortality at haulback with J-style hooks.  Significant differences in hooking location between the two hook types was found for night, blue, silky and oceanic whitetip sharks. These sharks were more commonly hooked externally vs internally.  No significant differences between hook types was found for the CPUE's on bottom longlines.  Significantly more blacknose were alive at haulback when circle hooks were used on bottom longlines. Bottom longlines were also used to test for differences in CPUE by fishing depth.  Demersal hooks had significantly higher CPUE's than those suspended in the water column for blacknose and nurse sharks and southern stingrays.

The effectiveness of 18/0 circle hooks, compared to 9/0 J-type hooks, in decreasing the incidental capture and post-release mortaliity of sea turtles was tested in the Brazilian pelagic longline fishery operating in the south-western Atlantic Ocean.  The incidental capture of loggerhead sea turtles was reduced by 55% and for leatherback sea turtles by 65% when circle hooks were used.  De-hooking also decreased from 25% to 5.8% in loggerhead sea turtles when circle hooks were used, likely increasing their post-release survival rates.  Catch rates of targeted species including bigeye and albacore tuna and blue sharks increased with the use of circle hooks, while no difference in catch rates between hook types was found for yellowfin tuna, shortfin mako or hammerhead sharks or for dolphinfish.  However, swordfish, another target species, catch rates were significantly reduced with the use of circle hooks.

An excluder grate (grid) was tested in the silver hake trawl fishery in Massachusetts Bay to determine it's effectiveness in reducing spiny dogfish bycatch.  The effects of color (white or black), angle and direction of the 50 mm spaced grids were investigated through video observations and data collection.  The number of spiny dogfish caught in trawls with the excluder grate were greatly reduced for all gear configurations, while the number of target species caught remained within typical commercial quantities.  Over 88% of spiny dogfish were excluded by the grate regardless of color or gear configuration.  There were no observed differences in the behavior of spiny dogfish between gear configurations or grate colors.

Analyses of the Hawaiian pelagic longline fishery were conducted to determine what factors, including hook type (J or circle) and location (sea mount v open ocean), have impacted the catch of both target and bycatch species.   Standardized catch rates for all tuna species as well as for blue and oceanic whitetip sharks were significantly higher when the wider circle hooks were used.  However, shortbill spearfish and striped marlin catch were significantly lower when circle hooks were used.  No differences in catch rates between the two hook types were seen for bigeye thresher sharks or swordfish.  The average swordfish lengths were significantly larger when circle hooks were used, while average lengths for bigeye and skipjack tunas were significantly smaller.  There was no difference in the average length between the two hooks types for yellowfin or albacore tunas, spearfish or marlins. In addition, the change from J hooks to circle was likely a factor in decling sea turtle bycatch rates. 

Pelagic stingrays (Pteroplatytrygon violacea) are a common bycatch species in the Mediterranean pelagic longline swordfish fishery. Experimental trials took place in the central Mediterranean Sea from 2005 to 2007 to investigate the importance of bait size, presence and type of light attractors, and hook size and shape on pelagic stingrays. Bait size and light attractants did not have a significant effect on stingray catch rate. Larger J-hooks reduced the stingray capture rate. 16/0 circle hooks had a significantly lower number of stingrays captured than J-hooks, up to 80%

Pelagic stingrays (Pteroplatytrygon violacea) are a common bycatch species in the Mediterranean pelagic longline swordfish fishery. Experimental trials took place in the central Mediterranean Sea from 2005 to 2007 to investigate the importance of bait size, presence and type of light attractors, and hook size and shape on pelagic stingrays. Bait size and light attractants did not have a significant effect on stingray catch rate. Larger J-hooks reduced the stingray capture rate. 16/0 circle hooks had a significantly lower number of stingrays captured than J-hooks, up to 80%

A study was conducted to determine the impact of removing the 'tickler' from in front of groundgear of trawls. The 'tickler' is a length of chain placed in front of the groundgear of trawl gear, which is supposed to increase catches of sharks and rays. Tests were conducted where the 'tickler' was removed and secondary nets (groundgear bags) were placed behind the groundgear to determine the amount and species of fish that escaped capture. The results indicated that removing the 'tickler' from in front of the groundgear reduced the capture of skates and sharks. Therefore, prohibiting the use of 'tickler' chains in critical habitats for skates and sharks could be a beneficial management tool.