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The Hawaii longline swordfish fishery reduced seabird captures through mitigating bycatch during setting. Now, 75% of bycatch occurs during hauling. Observer data was fit to a generalized additive regression model and found that density of albatrosses during hauling, leader length, and year had the largest model effects. Heavier swivels, greater than 65g, had significantly fewer catch rates for seabirds. However, heavier weights with longer leaders had reduced effects. Shorter leaders with weighted swivels closer to the hooks, significantly reduced the likelihood that baited hooks could become available to albatrosses at the surface. There was no significant difference in catch rate between hauls made with vs. without blue-dyed bait. Future haul mitigation should focus of reducing bird access to hooks as crew coil branchlines. 

Cory's shearwater, Calonectris diomedea, is the main seabird species incidentally caught by the Spanish longline fleet in the western Mediterranean Sea. The authors used onboard observer data to model the longline bycatch of Cory's shearwaters as a function of time of the year, technical characteristics of the fishing operation, and geographical location. The most explanatory factor for bycatch was the geographical location and then the technical characteristics (number of hooks and fishing during non-working days). Seabirds are more likely to approach longline vessels when trawlers are not allowed to operate (non-working days), so the authors conclude that activity of longliners should be limited to working days.  

This study examined the spatial and temporal variations in bycatch rates of four species of great albatrosses. Observer data was obtained from the Uruguayan pelagic longline fleet and Japanese vessles operating in Uruguay. Vessel operational practices and habitat variables affected bycatch rates, including: setting time, moon phase, and area and season. 

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.

Integrated weight longlines (IW) were tested for their ability to reduce sea bird bycatch in demersal longline fisheries. The target fishery for testing was the Pacific cod fishery operating in the Bering Sea, Alaska, USA. Three experimental mitigation techniques were tested: 1) IW line alone, 2) IW paired with streamer lines (IWPS) and 3) unweighted longlines with paired streamer (UWPS) against a control (UW). Information on catch rates, seabird abundance and attack rate, and gear sink rate and performance were collected. Seabird bycatch was dramatically reduced with all three experimental longlines. Surface foraging seabirds had higher reduction in mortality rates (91-100%) compared to diving seabirds (80-97%). The IWPS mitigation technique performed best because it allowed the gear to sink within the protection of the streamer, completely eliminated surface foraging and reduced shearwater catch by 97%. UWPS and IW reduced surface foraging catches rates by 98% and 91%, respectively. Shearwater catch rates were reduced by 87% with UWPS and 80% with IW. Catch rates of Pacific cod did not vary across mitigation techniques and the control.

Fisheries observer data from six gear types operating in the US Northeast and mid-Atlantic were analysed for seabird interactions. Between 1996 and 2014 an estimated 48,821 seabirds interacted with commercial fishing gear. This resulted in an estimated average interaction rate of 2,570 seabirds per year. The majority of interactions occurred in gillnet fisheries and involved shearwaters/fulmars. A comparison with previous work in the region was also conducted. This comparison highlighted the need for consistency in data preparation to relative trends in seabird bycatch in the region can be compared. Additional analysis should provide context for interaction estimates to allow for population-level impacts to be inferred.

Experiments on the use of sea bird mitigation methods were conducted aboard Uruguayan pelagic longliners between 2010 and 2012. Experiments looked at the difference between setting bait at the sea surface and setting baits underwater. The researchers recorded the abundance of sea birds following the vessel and incidences of attacks on bait and mortality. When the bait was set underwater, there was a marked reduction in the number of seabirds following the vessel and attacks on bait. Mortality levels of birds caught on bait set 4 m below the surface were 87% lower than mortality levels for birds when bait was set at the surface. There were no bird mortalities when bait was set 10 m below the surface. The mortality level of birds when bait was set at the surface was 11.6 birds/1000 hooks.  No differences in catch rates of target species (tuna) were observed when bait was set at the surface or below the surface.

Fishing-related seabird mortalities are considered the most pervasive threat to seabird conservation status. Specifically, warp wire interactions (warp strike) and net captures of trawl vessels in Australia’s Commonwealth-managed Southern and Eastern Scalefish and Shark fisheries has been identified as a growing concern. This paper describes an industry-led study that developed and tested the effectiveness of 2 experimental mitigation devices for trawl vessels: a "baffler" and a "water sprayer". These were tested against a control which was previously the only prescribed device, called a "pinkie". Seabird interactions were observed during 69 tests comparing the "sprayer" against the control, and 55 tests comparing the "baffler" against the control. Both experimental mitigation devices showed significant reductions in heavy interaction rates (interactions per test) compared with the "pinkie" (83.7 and 58.9%). Based on the findings from this study, the Australian Fisheries Management Authority now allows vessels to meet seabird bycatch mitigation requirements through use of either new device.

Researchers deployed LED lights on the floatlines of paired gillnets (control vs illuminated net) during 864 fishing sets using small-scale vessels departing from three Peruvian ports between 2015 and 2018. Bycatch probability per set for sea turtles, cetaceans and seabirds as well as catch per unit effort (CPUE) of target species were analyzed for illuminated and control nets using a generalized linear mixed-effects model (GLMM). For illuminated nets, bycatch probability per set was reduced by up to 74.4 % for sea turtles and 70.8 % for small cetaceans in comparison to non-illuminated, control nets. For seabirds, nominal bycatch per unit effort (BPUE) decreased by 84.0 % in the presence of LEDs. Target species CPUE was not negatively affected by the presence of LEDs. This study highlights the efficacy of net illumination as a multi-taxa BRT for small-scale gillnet fisheries in Peru.