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This study tested the use of an excluder grid with 90mm bar spacing to reduce bycatch of blackmouth catshark (Galeus melastomus) in  demersal trawl fisheries in the Mediterranean. The 90mm excluder grid was not very efficient in reducing blackmouth catshark bycatch because only the larger individuals were excluded, and the target catches of greater forkbeard fish (Phycis blennoides) and (to a lesser extent) Norwegian lobster (N. norvegicus) was reduced. Results of modeling suggest that reducing the grid bar spacing to 70mm would provide a better trade-off of reducing blackmouth catshark bycatch while keeping a high catch rate of greater forkbeard and Norwegian lobster.

This study investigated the use of two new elasmobranch bycatch reducing devices in a Mediterranean multispecies bottom trawl fishery- the shark excluder device (SED) and a flexible grid (Flexgrid). The SED was effective in reducing elasmobranch bycatch and did not impact mantis shrimp (Squilla mantis) target catch, but did reduce catch for some large bony fish species. The results from the Flexgrid were limited due to small sample size, but there was no impact on catch of main target species although a shark was incidentally caught. SED and Flexgrid could be combined with other conservation measures such as seasonal fishing closures to mitigate elasmobranch bycatch. 

This study investigated the use of two new elasmobranch bycatch reducing devices in a Mediterranean multispecies bottom trawl fishery- the shark excluder device (SED) and a flexible grid (Flexgrid). The SED was effective in reducing elasmobranch bycatch and did not impact mantis shrimp (Squilla mantis) target catch, but did reduce catch for some large bony fish species. The results from the Flexgrid were limited due to small sample size, but there was no impact on catch of main target species although a shark was incidentally caught. SED and Flexgrid could be combined with other conservation measures such as seasonal fishing closures to mitigate elasmobranch bycatch. 

This study investigated the effectiveness of retention bans for reducing shark mortality in longline and gillnet fisheries, as reported in 160 relevant studies across 341 shark species. Results suggest that retention bans can reduce shark mortality when averaged across all species, but that species with lower intrinsic population growth rates benefit less from a retention ban than those with higher rates of population growth. The authors stress that retention bans alone cannot address unsustainable shark bycatch and mortality, and that efforts should be combined with other mitigation measures such as spatial/temporal fishery closures. Smaller-bodied species are more likely to die at the vessel, whereas deep-water species are more likely to experience mortality post-release.

This review paper reflects on the past 50 years of efforts to save the vaquita (Phocoena sinus) from extinction, with the primary threat being lethal bycatch in gillnets set for the totoaba fish in the upper Gulf of California. Both the conservation goals for the vaquita and the economic and social goals for the local fisheries have consistently failed to meet even the lowest stakeholder expectations, and the vaquita population has continued to decline. The authors call for an "immediate and definitive decision" to either preserve the vaquita or aid sustainable fisheries in the region, being aware of the costs of either choice and similar conservation failure stories such as with the Yangtze River dolphin in China.

This summary study describes all identified fishing techniques that have been used globally to reduce unintended species bycatch, to improve clarity on available techniques and highlight opportunities for further research and development. Of the total 55 techniques identified, the majority are specific to long-line fisheries and to designed to benefit small mammals, seabirds, and sea turtles. Additionally, the majority of techniques (81%) attempt to avoid contact of bycatch species with fishing gear altogether, rather than attempting escape or release.

By modeling (GLMs and GAMs) data from onboard observers and logbooks, the authors investigated patterns in loggerhead sea turtle (Caretta caretta) bycatch in bottom trawlers in the Southern Adriatic Sea. Results indicate that most bycatch occurs during the daytime and in shallower coastal waters, and that it increases temporally in summer and autumn. The study also identified two bycatch hotspots: the Gargano promontory and off the coast of Brindisi.

This summary study analyzes unintended horsehoe crab (Tachypleus tridentatus) bycatch in trawl and gillnet fisheries in the Letzhou Gulf, China. Estimates show at least 9120 ± 315 horseshoe crabs are caught annually. Bycatch rates increase in spring and autumn, and are higher in gillnet fisheries compared to trawl fisheries. The study also highlights several zones/areas of the Letzhou Gulf with "abundant shoal resources" and higher bycatch rates.

The authors performed modeling on 10 years of logbook data to analyze environmental and operational factors that influence shark and odontocete depredation in the New Caledonian longline tuna fishery. Results suggest that there are "hotspots" of odontocete depredation, and that it is driven by environmental factors such as sea surface temperature and bathymetry, while shark depredation is driven by operational fisheries factors such as soaking time and number of hooks. Alterations such as reducing soaking time to under 12 hours, or setting limits on hooks to <1,750, could significantly reduce the likelihood of depredation. 

The authors developed a novel mitigation method for reducing seabird bycatch in gillnet fisheries in the Baltic Sea: looming-eyes buoys (LEB), an above-water visual deterrent. This method was trialed off of Sareemaa Island, Estonia, and was shown to reduce potential for long-tailed duck (Clangula hyemalis) bycatch by 20-30% within a 50m radius with a possible habituation effect within 62 days. These trials suggest that above-water visual deterrents such as LEBs could contribute to reduce seabird bycatch in combination with other management and mitigation measures.