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Experiments were carried out aboard vessels in the Danish North Sea hake (Merluccius merluccius) gillnet fishery to determine if increasing the spacing of Aqutec AQUAmark100 pingers could be done without negatively impacting the effectiveness of the pinger. Control nets without pingers were tested alongside nets with pingers spaced at 455 m and 585 m. The control nets had a bycatch frequency of 0.54 incidents/haul for harbour porpoises (Phocoena phocoena). Nets with pingers spaced at 455 m had an incidence rate of 0 and nets with pingers spaced at 585 m had a bycatch frequency rate of 0.12. Bycatch indences were significantly different between the control and two experimental groups. This suggests that the spacing of pingers may be increased without significantly impacting their ability to reduce bycatch of harbour porpoises. 

Fumunda acoustic alarms were tested in the absence of nets to determine their ability to modify the behavior of Australian snubfin (Orcaella heinsohni) and humpback dolphins (Sousa sahulensis), with possible applications to gillnet fisheries. The alarms emitted a regular interval pulse of 300 ms every 4 seconds at 10 kHz frequency.  The behavior of the animals changed slightly when the alarms were used but the likelihood of them leaving the area was not significantly different from the control.  This suggests this type of acoustic alarm may not be useful as a bycatch mitigation measure for these species.

Acoustic pingers (Dukane Netmark 1000; frequency of 10-12 kHz and emit 300 ms tone every 4 sec with a source level range of 120-146 dB) were assessed to determine the effectiveness for reducing bycatch of dolphins and porpoises (common dolphins (Delphinus delphis), dusky dolphins (Aethalodelphis obscurus), bottlenose dolphins (Tursiops truncatus), Burmeister's porpoise (Phocoena spinipinnis), and pilot whales (Globicephala sp.) by Peruvian small-scale driftnet fleets. Pingers were tested between April 2009 and August 2011. Twenty-two percent of the control nets captured small cetaceans and 16% of experimental nets captured small cetaceans. This was a 37% reduction in bycatch rates, suggesting that pingers may be effective in reducing bycatch of small cetaceans in this fishery. Catch rates of the fishery's target shark and ray species was not changed. 

Two harbor porpoises (Phocoena phocoena) were subjected to 3 different underwater sounds (standard Dukane alarm, random Dukane alarm, and a "bird alarm") in a enclosed floating pen. Their behavior during a 15 min test period was compared to behavior during a baseline 15 min period before the test and a recovery period after the test. All alarms resulted in increases in both the distance of the animals surfacing from the alarms and their respiration rates. The standard Dukane alarm and the bird alarm were more effective than the random alarm in inducing animals to swim away from the source. 

Two captive harbor porpoises (Phocoena phocoena) were exposed to three sound types (frequency from 100 kHz to 140 kHz, 200 ms long, and presented once per 4 s). Each session consisted of a 10 min period per sound, a 5 min period of sound, and a 10 min period after the sound. Behavior was recorded on video and with dataloggers. Animals reacted most to the initial presentations of sound, but the reactions diminished rapidly in repeated sessions. 

A field test was conducted to test whether harbor porpoises (Phocoena phocoena)  habituate to pingers over time. Echolocation and movements were monitored around a mooring equipped with a pinger (Dukane Netmark 1000) for 3 months. Initial displacement was 208 m from the pinger, but it diminished by 50% within 4 days. Echolocation rate and occurrence were significantly reduced near the pinger. 

This study qualitatively describes collisions between cetaceans and fishing boats on the Brazilian coast and the Central Amazon region through the perception of artisanal fishers. From 2005 to 2010, 215 interviews were conducted. Fishers identified encounters with five species: Inia geoffrensis, Sotalia guianensis, Tursiops truncatus, Eubalaena australis, and Megaptera novaeangliae. They said accidents occurred due to animal curiosity, high speed swimming, and calve protection. The authors propose co-management with local members, researchers, and the government to encourage feelings of collective ownership within communities aiming to minimize the number of collisions. 

Potential risk of fisheries to cetaceans was assessed using a screening procedure based on a Productivity Susceptibility Analysis (PSA) using gears found in Ireland. Gillnets targeting demersal species was assessed as the fishery posing the greatest risk to cetaceans. Pelagic trawls targeting small pelagic species was found to pose a moderate risk to cetaceans. Specific gear-species interactions were also identified, such as humpback whales (Megaptera novaeangliae) and pots/traps.  

The long-term effectiveness of acoustic pingers in reducing marine mammal bycatch was assessed in the California swordfish (Xiphias gladius) and thresher shark (Alopias sp.) drift gillnet fishery. Bycatch was observed at sea between 1990 and 2009, with acoustic pingers being present from 1996 to 2009. Bycatch rates of cetaceans decreased by around 50% when pingers were present; the decrease was mostly driven by common dolphins (Delphinus delphis). Beaked whales have not been incidentally caught since 1995. Pinger failure occurred in less than 4% of observed sets. Cetacean bycatch was 10 times higher in sets where more than one pinger failed. There was no evidence of habituation to pingers by cetaceans. Bycatch rates of California sea lions (Zalophus californianus) was almost double in sets with pingers than without, leading the authors to examine the "dinner bell" effect of pingers. Depredation of swordfish by sea lions was not linked to pinger use, instead the best predictors were total swordfish catch, month and area fished, and nighttime light use.   

Logbook and observer data were used to assess common bottlenose dolphin (Tursiops truncatus) bycatch patterns from 2003 to 2009 in the Pilbara trawl fishery. Dolphins were caught in all fishery areas, across all depths, and throughout the year. The bycatch rate from observers was 12.6 dolphins/1,000 trawls, which was double the rate reported in logbooks. The most significant predictors of dolphin catch were: vessel, time of day, and the use of bycatch reduction devices (BRDs). BRDs reduced catch by 45%.