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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. 

Illuminated nets were tested to evaluate their effect on catch and bycatch in set nets, principally green (Chelonia mydas) and loggerhead (Careta caretta) sea turtles, in northern Cyprus. Reductions in the catch of sea turtle and non-target sharks and rays were recorded with no effect on target catch. Data were collected from 130 field sets that occurred over a two-year period. Experimental effort should be expanded to better ascertain the relationship between the illuminated devices used and sea turtle bycatch reduction.

This study recorded and analyzed vocalizations of green sea turtles (Chelonia mydas) off the Caribbean island of Martinique, and identified which sounds seemed to be linked to flight, fear, and social aspects. When these recordings of sea turtles were played to wild sea turtles, they demonstrated behavioral responses (vigilance and/or escape) to the sounds they produce, suggesting that acoustic deterrents may be effective to reduce sea turtle bycatch. Sea turtles did not respond to synthetic or geophonic noises.

This study investigated bycatch events in the northern South China Sea through interviews of fishers. The majority of interviewed fishers reported an estimated 7,464 annual bycatch events, with sea turtles encountered most commonly followed by Indo-Pacific finless porpoises (Neophocaena phocaenoides), whale sharks (Rhincodon typus) and Indo-Pacific humpback dolphins (Sousa chinensis). The gear most associated with bycatch were gillnets, trawl nets, and seine nets. Modeling suggests that bycatch may be influenced by distance from the coast and water depth for marine mammals and sea turtles, but by administrative region for whale sharks.

The authors trialed the effectiveness of green LED lights to reduce sea turtle (primarily loggerhead, Caretta caretta) bycatch in bottom-set gill and trammel nets in the northeastern Adriatic Sea (territorial waters of Croatia and Slovenia) . The result was no significant change in sea turtle bycatch, and a significant decrease (35%) of primary target catch. Although net illumination has been highly effective (up to 93%) in reducing sea turtle bycatch in other regions, this study highlights the importance of regional variability in mitigation measures.

This summary study is a meta-analysis of experimental results from 41 studies that investigated bycatch mitigation methods for sea turtles in tuna and swordfish longline fisheries. Circle hooks demonstrated effectiveness in reducing sea turtle bycatch; however, these hooks also usually use fish bait instead of hook bait, which may also be leading to the reduction in bycatch. Additionally, outcomes varied between the Atlantic, Pacific and Mediterranean, which highlights the importance of regional data collection. Further studies of circle hooks with a wire appendage and blue light are encouraged.
 

By modeling (GLMs and GAMs) data from onboard observers and logbooks, the authors investigated patterns in loggerhead sea turtle (Caretta caretta) bycatch in bottom trawlers in the Southern Adriatic Sea. Results indicate that most bycatch occurs during the daytime and in shallower coastal waters, and that it increases temporally in summer and autumn. The study also identified two bycatch hotspots: the Gargano promontory and off the coast of Brindisi.

This letter briefly outlines actions taken by the five tuna regional fisheries management organizations (RFMOs) to reduce sea turtle bycatch in tuna and tuna-like fisheries. Recent initiatives include impact assessments, bycatch mitigation measures for pelagic fisheries, identification of sea turtle bycatch patterns in longline and perse seine tuna fisheries, and a joint tuna RFMO Bycatch Working Group meeting that took place in December 2019. 

The authors compiled fishing effort data from a nearly 20 year period across 18 different longline, gillnet and purse seine fisheries in the eastern Pacific Ocean in order to assess/model vulnerability of leatherback sea turtles (Dermochelys coriacea) to fishing impacts under 70 different conservation management measure (CMM) scenarios. To do this, a new ecological risk assessment approach, the Ecological Assessment for the Sustainable Impacts of Fisheries (EASI-Fish), was used. The CMMs of large circle hooks, finfish bait, and best handling and release practices each decreased vulnerability, but the most effective scenarios used all three measures together. EASI-phish was used as the ecological risk assessment.

This summary study assessed data from pelagic longline fisheries and sea turtle bycatch across 40 nations in the year 2000. Analyses showed that more than 200,000 loggerhead sea turtles (Caretta caretta) and 50,000 leatherback sea turtles (Demochelys coriacea) were likely taken as pelagic longline bycatch in 2000, which is not a sustainable level.