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Pearl Nets, a passive acoustic deterrent, were tested in commercial gillnet fisheries in the Western Baltic Sea. Compared to a control, the Peal Nets reduced harbor porpoise (Phocoena phocoena) bycatch and maintained target catch rate for Atlantic cod (Gadus morhua).

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.

 This study assesses bycatch and depredation  by sharks and odontocetes in the French Polynesian longline fishery between 2000 and 2018, and finds that less than 2% of the catch had been depredated, but shark bycatch was high (20,000 sharks annually, 0.5 shark every 1000 hooks). Conversely, odontocete bycatch was comparatively low  (13 occurrences in 18 years), though reporting may have been inaccurate. This is important as there is a plan to  double offshore fisheries production in the French Polynesia EEZ by 2027.

This study evaluated the cetacean interactions with a bottom-set net fishery along the mainland Portuguese Southern coast (Algarve) from 2018-2022. Depredation by bottlenose dolphins (Tursiops truncatus) occurred in 17.7% of hauls, while bycatch occurred in <1%. Depredation was elevated in the spring and winter months and in gears targeting red mullet (Mullus surmuletus) and hake (Merluccius sp.). 

This study investigated harbor porpoise (Phocoena phocoena)  bycatch in bottom gillnets and trammel nets targeting turbot (Scophthalmus spp.) in the Black Sea between 2019-2021 via independent observers, questionnaires and stranding data. Cetaceans were caught on 55% of trips, and most were harbor porpoises. The study confirmed that bycatch is the most serious and immediate threat to the Black Sea harbor porpoises, with as many as 16,200 individuals caught annually. 

This study investigated bycatch events in the northern South China Sea through interviews of fishers. The majority of interviewed fishers reported an estimated 7,464 annual bycatch events, with sea turtles encountered most commonly followed by Indo-Pacific finless porpoises (Neophocaena phocaenoides), whale sharks (Rhincodon typus) and Indo-Pacific humpback dolphins (Sousa chinensis). The gear most associated with bycatch were gillnets, trawl nets, and seine nets. Modeling suggests that bycatch may be influenced by distance from the coast and water depth for marine mammals and sea turtles, but by administrative region for whale sharks.