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This article reviewed bycatch mitigation methods that rely on sensory ecology to reduce interactions with sea birds, 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, excpet for cetaceans. Cetaceans require both visual cues and warning through echolocation.

The authors investigated the effects of a large-scale gillnet closure on sea bird populations in Canadian waters. After a 1992 closure, breeding populations of bycatch-prone diving birds (auks and gannets) increased, with a corresponding decrease in surface-feeding scavengers such as gulls that are less prone to bycatch in gillnets but that do consume fisheries discards.

Trials were conducted using excluder grids on trawls targeting Norway lobster (Nephrops novegicus) and greater forkbeard (Phycis blennoides) in the Tyrrhenian Sea. The excluder grids were tested for their ability to reduce the incidental capture of blackmouth catshark (Galeus melastomus).  In order to estimate the number of escaped fish, covers were placed over the escape outlet before the grid and over the codend. The 90 mm excluder grid did not result in reduced catches of blacknouth catshark. The grid did result in decreased catches of greater forkbeard and Norway lobster, to a smaller degree. Explorative simulations suggest a smaller grid spacing of 70 mm may prove more effective at reducing blackmouth catsharks catches.

Pelagic longline hooks equipped with magnets were tested for their ability to repel blue sharks.  Tests were conducted aboard pelagic longliners operating in the Northeast Atlantic Ocean. Two magnets, one large and one small, were tested. Magnets were manually attached to the hooks (polarized so the magnet field was oriented N or S and in parallel with the hook axis). Three test zones, each with 5 hooks with 1 magnet, 11 hooks with 2 magnets and 16 control hooks, were deployed along a longline. The results indicated that blue shark catch rates were not reduced with the use of magnets, and can instead have an increased attractive effect. The attraction was higher with the large magnet.

Depredation by antarctic fur seals (Arctocephalus gazella), sperm whales (Physeter macrocephalus) and orcas (Orcinus orca) were studied in a Patagonian toothfish (Dissostichus eleginoides) fishery operating around South Georgia. While sperm whales come in contact with about one third of longlines (averaged over 1997 and 2012), depredation events from this species were considered insignificant. Orcas interacted with only 5% (averaged over 1997 and 2012) of longlines, but can remove over half the catch during an interaction. Interactions with orcas are spatially limited to migration routes; however, fishing is concentrated in these areas during migrations times. Interactions with fur seals were the most frequent until 2009, averaging just under 9% from 1997-2012. The catch-per-unit-effort of toothfish was higher when no mammals were observed near longlines. 

The authors conducted a review of post release mortality studies on billfish caught in recreational fisheries. Despite relatively so few studies involving many variables, the authors were able to detect some trends: 1) High speed trolling with artificial lures or a lure/natural bait combination (usually with J hooks) result in low amounts of internal hooking, tissue trauma and post release mortality; and 2) slow troll fisheries using natural baits or lure/bait combinations and circle hooks result in reduced rates of internal hooking, tissue trauma and sometimes post-release mortality. 

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.

Experiments were conducted along the Swedish coast to investigate the impact of seal exclusion devices (SEDs) on seal bycatch. Pot entrances were fitted with SEDs of different shapes and sizes. The pots were a two-chambered single entrance floating cod pot. Pots were equipped with a 45 mm escape window. Experimental pots had vertically mounted metal frames that were secured with nylon line. Five different types of SEDs were used. They had different metal frames, different shapes, thickness of material or inner circumference. Bycatch of seals was reduced to zero when SEDs were used and the pots' catchability was not negatively affected. The symmetrical oval shaped entrance and larger rectangle shaped entrance (two smaller openings) increased the pots' catchability.

A study was conducted in the waters off the coast of Archipelago de La Maddalena (Italy) to determine the impact bottlenose dolphins 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 and red mullet while catches of scorpionfish 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 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 moralities only recorded for common dolphins. Estimated annual mortality rates for the common dolphin are 113 individuals.