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The addition of a prototype "tunnel excluder" consisting of a filter grid (inclined at ca. 20 degrees) that leads to an escape tunnel in the Mauritanian industrial trawl fishery nets achieved a 40-100% reduction in bycatch of vulnerable species, including allowing 100% of rays and turtles to escape, 75% of manta rays, 40% of billfish and between 20-75% of sharks to escape. Cetaceans were less likely to use the tunnel to escape due to the narrowness of the design. 

To improve bycatch mitigation of chondrichthyans, reptiles and cetaceans for a tropical demersal fish-trawl fishery, species-specific responses to bycatch reduction devices (BRDs) were investigated using both in situ subsurface and onboard observations. This study combined in-net and onboard (774 day trawls and 1320 day trawl hours of subsurface observer coverage) electronic monitoring on all fish-trawl vessels (n = 3) to compare bycatch mitigation performances among nine megafauna groups, based on escape rates and interaction durations for three BRDs over 6 months (June to December 2012). Overall, 26.9% of day trawls had no megafauna interactions and 38.3% of the 1826 interactions escaped, with most in rapid time (91.4% in ≤ 5 min). The upward inclined exclusion grid significantly improved the escape proportions for most chondrichthyans by 20–30%. All BRDs were highly effective in reducing reptile (turtles and sea snake) bycatch, but irrelevant for the few sawfish (n = 13) that readily entangled in the anterior of the net. Cetacean (bottlenose dolphins, Tursiops trunactus, only) interactions with BRDs were very rare (n = 7) despite high levels of attendance and depredation during trawling. Loss of targeted teleosts through the BRD hatch was rare (1.3% of day trawls). This relatively cost-effective method of electronic monitoring achieved very high levels of subsurface observer coverage (60% of day trawls or 56% of day trawl hours), and provided evidence that the subsurface expulsion of megafauna in poor condition is negligible. Furthermore, this study provides species-specific improvements toward bycatch mitigation strategies for demersal fish trawling.

Tests were conducted aboard Canadian longline vessels targeting swordfish (Xiphias gladius) to determine if there were differences in the catch rates and size composition of swordfish and bycatch species caught by monofilament and multifilament nylon gangions.  No significant differences in the mean lengths of swordfish were found between the two nylon gangions but catch rates did differ significantly, with more swordfish caught on the monofilament gangions. There was also a significant difference in catch rates between the two gangions for blue sharks (Prionace glauca) and pelagic stingrays (Dasyatis violacea), with more animals caught on monofilament gangions. There was no significant difference in catch rates between gangions for mako sharks (Isurus oxyrinchus), white marlin (Tetrapturus albidus) or loggerhead sea turtles (Caretta caretta).

An experimental leader design was tested on pound nets in the Chesapeake Bay, United States, in 2004 and 2005 to determine their effectiveness in reducing the incidental catches of sea turtles (Lepidochelys kempi and Caretta caretta). 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. 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. 

Use-intensity distributions for 135 satellite-tracked adult leatherback turtles (Dermochelys coriacea) 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.  

The proven effectiveness of a bycatch reduction technology (BRT) does not guarantee its adoption by fishermen. This case study evaluated the willingness of Sicilian longline fishermen to use relatively large circle hooks (16/0) as a BRT for loggerhead sea turtles (Caretta caretta). Fishermen tested circle hooks with their fishing vessels and their own commercial fishing gear, and their opinnions before and after trials at sea were recorded. Fishermen said that they would be willing to use circle hooks in months with a high probability of bycatch if an economic incentive was provided and there was also public acknowledgement of their efforts. 

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 biting behavior of the loggerhead sea turtle, Caretta caretta, a common bycatch species in longline fisheries, was studied on 30 wild specimens held temporarily at rescue centers. Chemicals from squid baits elicited significantly more biting behavior than those from mackerel baits. 

Although counting nesting females and nests has been widely used to assess sea turtle abundance, surveys of in-water populations can provide a more effective means of measuring the success of recovery actions. Here, the bycatch of turtles recorded in observer data from fishing trips in the Pamlico-Albemarle Estuarine Complex, North Carolina (United States), from 1995−1997, 2001−2003, and 2007−2009 was leveraged to identify changes in species composition and overall abundance throughout the three different fishing periods. A significant increase in loggerhead (Caretta caretta) captures was detected among the three sampling periods, while the addition of sampling in 2007−2009 revealed significant increases in capture rates of green (Chelonia mydas) and Kemp’s ridley (Lepidochelys kempii) sea turtles. Loggerheads also dominated in the early sampling periods to an equivalent proportion of green and loggerhead sea turtles in 2007−2009. Long-term in-water studies such as this are critical for monitoring trends in sea turtle populations and implementing effective conservation plans.

Incidental catch of the loggerhead sea turtle (Caretta caretta) in the Mediterranean basin is the main threat to its conservation. In this basin, fisheries are multi-species, multi-gears and multi-national, making demersal fishing activities profitable, while preserving sea turtles is a challenge. In this study, scientists developed bycatch reducer devices and alternative fishing gears to mitigate the impact of demersal fishing gears on sea turtles. This included (i) testing hard and flexible Turtle Excluder Devices in bottom trawling nets and (ii) using ultraviolet LEDs as visual deterrents to illuminate set nets to avoid entanglement. The results of this study suggest the different devices did not affect the commercial catch, while bycatch reduction was instead evident. These results advocate for a global effort to introduce bycatch reduction devices in different areas and fisheries of the Mediterranean.