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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 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.

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 evaluated the effectiveness of DDD®03H Dolphin Dissuasive Devices, or DDD pingers (an acoustic deterrent device) to reduce common dolphin (Delphinus delphis) bycatch in a demersal pair trawler in the Bay of Biscay. Results showed that the DDD pingers reduced common dolphin bycatch by more than 90%, and that common dolphin bycatch in this trawl fishery is related to fishing zone and depth, but not necessarily factors such as time of day and haul duration.

The authors performed onboard surveys (line transects and passive acoustic monitoring) and interviewed gillnet fishers to assess abundance and bycatch of the endemic Burmeister’s porpoises (Phocoena spinipinnis) in northern Peru in 2023. The population abundance in the study area was estimated at 1,696 spatially distributed individuals, with the highest densities found within 25km of shore and within shallow waters ≤50 m. Fishers' descriptions of bycatch aligned with survey results, and most fishers reported experiencing porpoise bycatch the previous year. The annual bycatch rate was estimated to be 420 porpoises across the entire artisanal gillnet fishery of Salaverry, which far exceeds sustainable limits and highlights the urgent need for bycatch mitigation measures.

The authors evaluated factors influencing marine mammal bycatch in static net fishing operations in the UK between 1996 and 2023. Since 2014, harbour porpoise (Phocoena phocoena)  bycatch has been decreasing while common dolphin (Delphinus delphis) bycatch has been increasing; grey seal (Halichoerus grypus) and harbour seal  (Phoca vitulina) bycatch has been increasing gradually across the time period. Influential factors included seasonal patterns, water depth, and level of fishing effort. 

An analysis of records of static net bycatch sampling in the United Kingdom from 1996-2023 found that use of acoustic deterrent devices (ADDs) reduced harbor porpoise (Phocoena phocoena) bycatch per haul (BpH) to 0.23 of the background rate. BpH increased for harbor seals and grey seals (Phoca vitulina and Halichoerus gryphus) when ADDs were used. Current efforts to reduce harbor porpoise bycatch may be increasing seal mortality in the same fisheries. 

Three types of acoustic deterrent devices were tested in the Icelandic cod gillnet fishery:  Fishtek Banana pingers, Porpoise ALert devices (PAL), and wideband PAL (wPAL) with a modified pinger signal (PAL device emitting a wideband pinger signal with a frequency range of 20 – 160 kHz and signal duration of 0.3 s (every 4–30 s) with the same source level at 145 db and maximum depth (320 m)). Banana pingers and PALs did not demonstrate any reduction of bycatch of marine mammals, while the wPAL-equipped nets had no bycatch during the trial. Fish catch and overall commercial value was significantly reduced in gillnets equipped with banana pingers and PALs.