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This article reviewed bycatch mitigation methods that rely on sensory ecology to reduce interactions with seabirds, sea turtles, pinnipeds and blue-water fish. Panels containing patterns of low spatial frequency and high internal contrast can be used for all of these species. These panels are not likely to reduce catches of target species and are easy and inexpensive to apply. The authors suggest that sound signals on gillnets are not recommended for most bycatch species, except for cetaceans. Cetaceans require both visual cues and warning through echolocation.

A Leslie Matrix model was used to simulate the impact of bycatch mortality on the narrow-ridged finless porpoise (Neophocaena asiaeorientalis). Based on the model results, there is an annual rate of decrease of 0.671 to 3.87%, with a population reduction of 29.6 to 86.3% over three generations. The most optimistic simulation showed at least a 30% reduction in population size. Therefore, reported bycatch mortality rates pose a substantial threat to this species.

A study was conducted in the waters off the coast of Archipelago de La Maddalena (Italy) to determine the impact bottlenose dolphins (Tursiops truncatus) had on gillnet fisheries targeting a variety of fish species. The study showed that the catch per unit effort of target species was significantly higher when there were no dolphin interactions. There were also differences in the species composition of nets attacked and not attacked by dolphins. Those nets attacked by dolphins showed a reduction in the catch of cuttlefish (Sepia officinalis) and red mullet (Mullus surmuletus) while catches of scorpionfish (Scorpaena spp.) increased. In nets not attacked by dolphins, red mullet was the most common species. In nets attacked by dolphins, scorpionfish were the predominate species caught. 

A study was conducted on observed interactions between a Portuguese purse-seine fishery and cetaceans. Cetaceans, primarily common dolphins (Delphinus delphis), were present during 16.9% of fishing events. The majority of these occurrences happened during the summer and early fall, and during the night. The presence of cetaceans was significantly linked to sardine (Sardina pilchardus) catches, effort and latitude/longitude. Encirclement of cetaceans occurred in 2.3% of fishing events, with moralities occurring in 1%. Common dolphin, bottlenose dolphin (Tursiops truncatus) and harbor porpoise (Phocoena phocoena) were all encircled, with mortalities only recorded for common dolphins. Estimated annual mortality rates for the common dolphin are 113 individuals.

A survey was conducted with fishers in Galicia Spain to investigate interactions between fishing gear and cetaceans. Cetacean fishery interactions appear to be frequent events. Although the damage to the catch and fishing gear were generally reported to be small, substantial economic loss can result from interactions with common bottlenose dolphin (Tursiops truncatus) and coastal gillnet fishing gear, and from short-beaked common dolphins (Delphinus delphis) interactions with purse seine fisheries. Bycatch mortality for cetaceans was reported to be highest in trawl and set gillnet fisheries.

A desk-based study was conducted to evaluate 'conservation-relevant elements' of local governments involved in coastal and aquatic resource management, particularly bycatch mitigation. Four sites were looked at: 1) Trat, Thailand, 2) Mahakam River, Indonesia, 3) Malampaya Sound Philippines and 4) Guimaras and Iloilo Straits, Philippines. The species of interest was Irrawaddy dolphin (Orcaella brevirostris) caught in small-scale fisheries. Several attributes were looked at including; extent to which conservation-relevant governance elements are active and effective, contribute to enforcement, coordinate across institutions and engage communities. These attributes appeared to vary across sites with noticeable differences between Malampaya Sound and Trat. Malampaya Sound has mostly low ratings for the assessed attributes, compared to high ratings for Trat. Involvement of local communities and support from external institutions were determined as being necessary. Bridging organizations were some of the most active, effective and engaged institutions at all of the sites.

A spatially and temporally explicit Productivity and Susceptibility Analysis (PSA) was developed to screen cetacean species for bycatch risk. This PSA can be included under Ecosystem Based Fisheries Management (EBFM). The potential risk to harbor porpoises (Phocoena phocoena) and minke whales (Balaenoptera acutorostrata) from static fishing gear was investigated. Harbor porpoises had a low- to moderate- biological risk from bycatch compared to other cetacean species. Minke whales are less productive than harbor porpoises but also have a low to moderate biological risk to bycatch. The results suggested that high, low and moderate risk areas can all exist within the range of individual fisheries (gillnet, longline, pots). Therefore, management measures can focus on areas of the greatest risk to these species. EBFM can complement and support current management measures.

This study collected information on cetacean incidents (carcasses, injured and debilitated animals found onshore, entrapped in shallow water, entangled or floating offshore) that have occurred in New South Wales, Australia. Information on marine mammal incidents was reported to the New South Wales National Parks and Wildlife Service and recorded into a Marine Fauna Events Database. This information was analyzed for trends in mortality and population dynamics such as age and sex ratios. Records existed for the time period of 1790 to 2013. For the majority of incidents, the cause of mortality/morbidity could not be determined. Anthropogenic causes, such as entanglements, accounted for more incidents compared to natural causes such as disease or predation. Entanglement was the largest cause of cetacean incidents that were made up mostly of humpback whale (Megaptera novaeangliae) entanglements. Reporting of incidents have increased over time, from 1.3 incidents per year prior to 1960 to 43.5 per year during 2010, 2011, 2012 and 2013. A concentration of incidents were found in the Northern Rivers and North Coast regions. This study highlights the importance of these types of databases.

Documented entanglement cases for sea turtles and cetaceans in mussel aquaculture gear worldwide were collected. Online surveys and semi-structured interviews with mussel operators were used in Iceland. A total of seven entanglement reports were collected, four baleen whales, one harbour porpoise (Phocoena phocoena) and two leatherback sea turtles (Dermochelys coriacea). Mussel spat collecting ropes were involved in the majority of cases. Out of the seven reports, two occurred in Iceland. The proximity between cetacean distributions and mussel farming sites is likely a factor in these interactions. In addition, in Icelandic summer spat collection occurs when the largest concentrations of cetaceans are found in its waters. Iceland should consider some sort of mandatory reporting system for these interactions.

A quantification of interactions between cetaceans and fishers was conducted in the Atlantic and Indian Oceans. A large database of captains logbooks, 1980-2011, was analyzed along with scientific observer observations recorded between 1995 and 2011. The main areas of high co-occurrence between cetaceans and fisheries was shown to exist east of the Seychelles from December to March, the Mozambique Channel between April and May, and in offshore waster of Gabon between April and September. Cetacean associated fishing sets occurred in 3% of sets in both oceans and 0.62% of sets has encircled cetaceans. Survival rates for encircled cetaceans appear to be high. This suggests setting nets close to cetaceans has a low immediate impact to the individual species.