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Visual cues are important in sea turtle foraging behavior and likely influence their interaction with fishing gear. This studey examined the potential effectiveness of three visual cues: 1) shark shapes, 2) illumination of nets by LED lights, and 3) nets illuminated with chemical lightsticks - for reducing green sea turtle bycatch in gillnets. The presence of shark shapes significantly reduced mean sea turtle catch rates by 54%, but also reduced target catch by 45%. Nets illuminated with LED lights significantly reduced sea turlte bycatch by 40% and had negligable impact on target catch. Lastly, nets illuminated with chemical lightsticks also reduced sea turtle catch rates by 60% and had no significant impact on target catch. 

An experimental leader design was tested on pound nets in the Chesapeake Bay in 2004 and 2005 to determine their effectiveness in reducing the incidental catches of sea turtles.  The experimental design consisted of replacing the top two thirds of the traditional mesh panel leader with vertical ropes spaced 61 cm apart. During the study, 21 sea turtles interacted with the control net, while only 1 interaction with the experimental net occurred, which was a significant difference.  In addition, there was no significant differences in the harvest weight or size selectivity of finfish between the two net types, although these results were not considered very robust. 

An experimental leader design was tested on pound nets in the Chesapeake Bay in 2004 and 2005 to determine their effectiveness in reducing the incidental catches of sea turtles.  The experimental design consisted of replacing the top two thirds of the traditional mesh panel leader with vertical ropes spaced 61 cm apart. During the study, 21 sea turtles interacted with the control net, while only 1 interaction with the experimental net occurred, which was a significant difference.  In addition, there was no significant differences in the harvest weight or size selectivity of finfish between the two net types, although these results were not considered very robust. 

Tests were conducted aboard pelagic longline vessels fishing off the coast of Uruguay, to determine the effect of hook type (circle hook vs J-hook) on the catch and length composition of target and non-target species.  Both American and Spanish style longlines were used during these experiments.  American style longlines consist of a 3.6 mm polyamide monofilament mainline with polyamide or polyester buoys lines 9-36 m long.  Spanish style longlines consist of 5-mm polyethlene multifilament mainline with buoy lines (similar in thickness and material to mainline) 12-18 m long.  On the American style longlines, albacore tuna and shortfin mako shark catches were significantly higher on circle vs J-hooks. Catches of other tunas and sharks (blue and porbeagle) were also higher on circle hooks, but were not significantly higher.  There was no significant difference in the catches of seabirds or sea turtles between the two types of hooks on the American style longlines.  On the Spanish style longlines, albacore tuna catches were also significantly higher on circle compared to J-hooks, and there was a significant decrease in pelagic stingray catches on circle hooks.  No significant difference in the catch rates of seabirds or sea turtles was seen between the two types of hooks on this type of longline.  There was no significant difference in the length distribution for any species between the two hook types on either type of longline.  There were also no significant differences between hook types for any hooking location of incidentally caught sea turtles.

Two experiments were conducted to determine if 1) UV illumination reduced green sea turtle capture rates in large mesh gilllnets and 2) what was the impact of UV illumination on target catch rates in bottom-set gillnets.  Paired tests were conducted using a control net and an experimental net with UV LEDs placed every 5 m on the floatlines for the sea turtle experiment.  In the target catch experiment, inactive LEDs were also placed on the control net at 5 m spacing's.  Sea turtle catch rates were significantly higher in the control nets and there was a 39.7% reduction in mean catch rates with the experimental net.  There was no significant difference in catch rates of target species between the control and experimental nets.

An observer program assessed the impact of the Costa Rican longline fishery on bycatch species from 1999 to 2010. Observers recorded species, sex, reproductive state, and dimensions of all animals captured. They also recorded information about individual longlines, including location, set and haul back times, hook type, hook number, bait used, target species, and total number of hooks. The longline fishery caught a large number of silky sharks (Carcharhinus falciformis), olive ridley turtles (Lepidochelys olivacea), and pelagic stingrays (Pteroplatytrygon violacea). The authors estimate that 699,600 olive ridleys were caught between 1999 and 2010, including 92,300 adult females. The captures correspond with a decline in nesting populations nearby and statistically significant size decreases in mature turtles. They also observed a decline in the average size of silky sharks. Geospatial analysis of the data indicated that there were temporal shifts in mahi-mahi abundance, but fishing efforts did not shift with abundance. The authors suggest marine protected areas and/or time area closure to reduce the bycatch of sea turtles and sharks.  

An analysis of the performance of circle hooks in comparison to J-style and tuna hooks on the hooking rates of target and non-target species, specifically sea turtles, in the artisanal surface longline fisheries of Ecuador, Panama, and Costa Rica was performed. The target fisheries were mahi-mahi and a combination of tunas, billfishes, and sharks (TBS). In the TBS fishery, tuna hooks were compared to 16/0 circle hooks from Ecuador and Panama and 18/0 circle hooks from Costa Rica. For the mahi-mahi fishery, 14/0 and 15/0 circle hooks in Ecuador and 16/0 circle hooks in Costa Rica were compared to traditional J-style hooks. Circle hooks reduced sea turtle hooking rates in most of the comparisons. Hooking rates for target and non-target species were not consistent.

Use-intensity distributions for 135 satellite-tracked adult leatherback turtles were combined with longline fishing effort to estimate predicted bycatch risk over space and time in the Pacific Ocean. For western Pacific nesting populations, the greatest risk was adjacent to primary nesting beaches in the tropical seas of Indo-Pacific islands. For eastern Pacific nesting populations, the greatest risk was in the South Pacific Gyre. Targeted management should be based on these predicted hotspots to reduce leatherback bycatch.  

Experimental studies were conducted over a three year period (August 2008-December 2011) to determine the effects of changing traditional J-hooks baited with squid bait to circle hooks (offset and non offset) with mackerel bait on sea turtle interactions. Studies were carried out aboard pelagic longline vessels targeting swordfish in the tropical northeast Atlantic Ocean. Overall, sea turtle interactions were reduced when circle, compared to J-hooks were used. However species specific differences did occur. Leatherback interactions were only reduced when circle hooks with an offset were used. Leatherback interactions can be reduced by 55% in this fishery by switching from J-style to circle hooks. Hardshell turtle interactions were reduced when both circle hook styles and mackerel bait were used. Interactions with hard shelled turtles can be reduced by 50-55% in this fishery by switching from J-style to circle hooks.  A 55% reduction in hardshell turtle bycatch is expected to occurr in this fishery by switching from squid to mackerel bait.

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.