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Researchers deployed LED lights on the floatlines of paired gillnets (control vs illuminated net) during 864 fishing sets using small-scale vessels departing from three Peruvian ports between 2015 and 2018. Bycatch probability per set for sea turtles, cetaceans and seabirds as well as catch per unit effort (CPUE) of target species were analyzed for illuminated and control nets using a generalized linear mixed-effects model (GLMM). For illuminated nets, bycatch probability per set was reduced by up to 74.4 % for sea turtles and 70.8 % for small cetaceans in comparison to non-illuminated, control nets. For seabirds, nominal bycatch per unit effort (BPUE) decreased by 84.0 % in the presence of LEDs. Target species CPUE was not negatively affected by the presence of LEDs. This study highlights the efficacy of net illumination as a multi-taxa BRT for small-scale gillnet fisheries in Peru. 

A long-term study assessed the efficiency of acoustic pingers (AQUAmark 100, 20-160kHz) in reducing the encounter rates of finless porpoises (Neophocaena spp.) with fishing nets. The study used a passive recorder to obtain acoustic encounter rates of echolocating finless porpoises over two eight-month periods. Encounter rates were significantly lower in periods when pingers were in use, but this effect decreased over time. By the end of each study period, the number of encounters was greater than those during periods without pingers, suggesting that habituation had occurred. However, when pingers were reactivated after four months of no use, encounters returned to lower levels, such as those observed during the beginning of the experiment. The results suggest that habituation to pingers may be mitigated by alternating periods of silence with periods of active pinger use. 

The study combined fisher questionnaires, acoustic monitoring, and participatory experiments to investigate the occurrence of bottlenose dolphins (Tursiops truncates) in the gillnet fisheries of Northern Cyprus. Dolphins were present in fishing grounds throughout the year, and were detected at 28% of net sets. Net damage was six times greater when dolphins were present during sets. Use of an acoustic pinger (AQUAmark 200, 5-160kHz) was tested, but had no significant effect on dolphin presence. 

The experiment evaluated the effectiveness of two types of pingers (Aquamark 100 and Aquamark 200) to reduce the bycatch rate of harbor porpoise (Phocoena phocoena) in a set gillnet fishery in the Black Sea. The study also evaluated the effects of the pingers on catch of target and non-target fish species. There was no significant difference in catch of target and non-target fish species in trials with pingers versus control sets. There was also no significant difference between number of harbor porpoises caught in nets using pingers and when no pingers were used, although a low overall number of porpoises were caught (eight harbor porpoises were caught during the experiment – three in control nets, three in nets using the Aquamark 100, and one in nets using the Aquamark 200). 

This study examined spatial interactions between false killer whales (Pseudorca crassidens) and the Hawaii-based deep-set longline fishery. False killer whales occur as bycatch in this fishery at rates that exceed allowable levels. Five satellite tagged whales (occurring within three groups) in combination with logbook entries showed that only two groups of whales approached gear at a distance closer than 50km. On two occasions, whales from one group came close enough to interact with gear, and one of six sets involved had no catch which may be explained by depredation. The haul phase showed the highest “attraction effect,” and the results suggest this portion of fishing activity may be an important factor in bycatch.

This study was a controlled experiment within in a harbor that investigated the effectiveness of attaching small, reflective objects (8mm wide acrylic glass spheres) to standard gillnets to increase acoustic reflectivity and therefore mitigate bycatch of small, echolocating cetaceans.  The study found that the spheres increased the acoustic backscattering strength and echo, which suggests that the spears would be an effective way to reduce small cetacean bycatch. Gillnets with sphere-sphere distance of 20cm performed best. 

Science Letters: In 2022, Mexican authorities placed hundreds of concrete blocks with entangling metal hooks to discourage gill net use; as a result, there has been a substantial decline in gill net use in the area, and healthy vaquitas(Phocoena sinus) have been observed. However, in order to fully protect the vaquita from extinction, more of the population's distribution area need to be protected from gill nets.

This summary study provides the  first global meta-analyses  of small- and large-scale gillnet odontocete bycatch  during 1990–2020, and estimates that annual gillnet bycatch in this timespan is 50,000 odontocetes. It highlights the need for improved management of gillnet fisheries worldwide, noting that effective methods (spatial closures, deterrent devices, gear modifications, etc.) will vary depending on region and species, such as using acoustic deterrents in river ecosystems or electric barriers in the open ocean. 

In the Indian Ocean tuna gillnet fisheries, cetacean bycatch is very high, but it is understudied and poorly understood. This paper investigates the issue and makes specific recommendations to strengthen knowledge and management: improve catch and bycatch reporting, increase research and analyses of cetaceans in the region in order to assess bycatch, revise the conservation measure adopted to address the bycatch of cetaceans in IOTC fisheries (Resolution 23/06) to include additional reporting for gillnets operating in EEZs, and expand the use of mitigation methods, such as setting gillnets 2m below the surface.

This article summarizes cetacean strandings along the Bulgarian coast of the Black Sea between 2010-2022. Of a total 1,528 strandings, evidence of bycatch was present in 80 animals. The presence of strandings with signs of bycatch even during the seasonal bans on turbot (Scophthalmus maeoticus) fishing suggests that illegal, unregulated, and unreported (IUU) fisheries may be operating.