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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 (Totoaba macdonaldi) 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 stakeholder expectations, and the vaquita population has continued to decline. The authors call for an "immediate and definitive decision" preserve the vaquita and aid sustainable fisheries in the region. 

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.  

The study examined individual and cumulative bycatch during the first five years of a fisher engagement program in the tuna drift gillnet fishery in Pakistan, where fishers co-developed a sub-surface net setting strategy while also receiving bycatch awareness and safe release training. Captain identity and year were the strongest predictors of sea turtle and dolphin bycatch rates.  

The PearlNet aims to mitigate odontocete bycatch in bottom-set gillnets by enhancing the acoustic visibility of nets through the incorporation of small, acrylic glass spheres. This study found that PearlNet performed similarly to standard nets in terms of catch efficiency and handling time of gear. Performance of the gear in reducing marine mammal bycatch was not assessed during this study, however, no mammal bycatch was reported. 

Between 2019 and 2022, trials using three different pinger models (Future Oceans 10 kHz, Future Oceans 70 kHz, and PAL Wideband) were conducted in Bulgaria during standard turbot (Scophthalmus maeoticus) fishing operations. Marine mammal bycatch was observed in  61% of all hauls. No significant difference in bycatch rates between active and control nets was observed in trials involving Future Oceans 10 kHz (17 trials) and 70 kHz (6 trials) pingers. However, a significant reduction (74%) in cetacean bycatch was recorded during the trials conducted with PAL Wideband pingers.