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This study examined the effectiveness of three electronic bycatch reduction devices with different signal frequencies and duty cycles (100% duty cycle fixed signal, 50% duty cycle fixed signal, 100% duty cycle quasi-random signal) in a laboratory experiment on Atlantic dogfish (Squalus acanthias). The results suggest that time-varying electrical signals can deter spiny dogfish from baited hooks. The researchers observed a reduction in bait consumption, mean bite rate, and probability of bait consumption from all three prototypes . The lowest bait consumption occurred with the 100% duty cycle, fixed-signal BRD, while the largest treatment differences resulted from the BRD with 100% duty cycle emitting a quasi-random frequency. 

This study evaluated the effectiveness of updated best handling and release practices, as well as a custom-designed shark release ramp, in improving the post-release survival of sharks onboard a U.S. purse seine vessel. 98.5% of sharks were released using the ramp system, with release times averaging under two minutes. 47% of captured sharks exhibited poor or moribund condition at haul-back. Tagging data from three released sharks indicated survival or likely survival post-release. While the ramp system with a hopper improved operational efficiency and enhanced crew safety, wider tagging efforts is needed to validate improved survivability of sharks post-release. 

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. 

The use of circle hooks (4.3 sun and 5.2 sun) instead of standard Japanese tuna hooks (3.8 sun) in the pelagic longline fishery in the western North Pacific, had little impact on catch rates, mortality or size composition of blue sharks (Prionace glauca).

Catch rates of blue marlin (Makaira nigricans), snake mackerel (Gempylus serpens), and sharks were lower when nylon monofilament leaders, instead of wire leaders, were used on pelagic longline gear, but bigeye tuna (Thunnus obesus) and black marlin (Makaira indica) catch rates increased. There was no effect on yellowfin tuna (Thunnus albacares). Nylon leaders also had higher bite-off rates than the wire leaders.

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.

Gillnets with three difference mesh sizes (2 7/8", 3" and 4") were modified to use 200 lbs/200 yard lead line and 11 oz buoyancy floats (versus 50lbs/200 yard lead line and 3 oz floats) to increase the tension in the net. Catch rates of Atlantic sharpnose (Rhizoprionodon terraenovae) and bonnethead (Sphyrna tiburo) sharks were significantly lower in the 4" modified net. The proportion of hammer-wrapped bonnethead sharks was significantly higher in the 4" unmodified net and significantly less blacktip sharks (Carcharhinus limbatus) were wrapped in the 3" modified net. Selectivity of blacknose sharks (Carcharhinus acronotus) varied between the modified and unmodified nets. Catch rates of targeted Spanish mackerel and spot were not significantly different between modified and unmodified nets.

The potential of modifying gillnets to reduce shark bycatch was investigated in the US Spanish mackerel (Scomberomorus maculatus)  and spot (Leiostomus xanthurus) gillnet fisheries. The modified net had larger floats on the head-rope and increased weight on the lead-line to increase the tension of the net. Results showed that the catch rate of some shark species was significantly reduced in the modified gillnets. Target catch rates of Spanish mackerel did not differ significantly between control and modified nets of the same mesh size.

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).

Neodymium-iron-boron (Nd2Fe14B) permanent magnets were used to test behavioral responses in spotted catsharks (Scyliorhinus canicula) and thornback skates (Raja clavata). Both species significantly avoided the Nd2Fe14B magnets more often in comparison to the control and procedural control and they fed significantly more from the control and procedural control in comparison to the magnets. The study also demonstrated a correlation between avoidance speed and distance with water temperature.