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This paper reports on successful seabird mitigation methods implemented in a Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)-managed fishery. The sub-Antarctic Patagonian toothfish (Dissostichus eleginoides) fishery had a high seabird bycatch mortality rate, particularly of black-browed albatross (Thalassarche melanophris) and white-chinned petrels (Procellaria aequinoctialis) when it began (>5,000 birds per 1,000 hooks). Due to successful mitigation measures and compliance, the fishery has since significantly reduced its seabird bycatch(<0.01 bird per 1,000 hooks). A multitude of measures were implemented, and the following measures are considered to have been important in reducing mortality: restricting the fishery to only operating in the austral winter, using novel marked hooks, 100% observer coverage, restricting longline setting to only occur during nighttime, and requiring weighted hooks so that lines sink rapidly. 

Using modeling (specifically Bayesian multilevel network meta-regression modelling), this  study presents a synthesis of the effectiveness of alternative pelagic longline weighting in mitigating seabird bycatch.  There is a high probability (97%) that all weighting designs do reduce seabird bycatch when compared to no weight, but the designs with weights >60g and >1m from the hook performed significantly better than designs with less weight but attached closer to the hook. 

This paper assessed richness, distribution, and incidental catch of benthic sessile invertebrates in the Great Amazon Reef System (GARS)  based on records and photographs collected from onboard observers between 2015 and 2022. In total, 54 distinct species were recorded as bycatch, with most being echinoderms. Gillnet and trawl fisheries pose the greatest threats to the GARS, and over time this bycatch may profoundly disturb benthic reef communities and therefore reduce fishery yields.

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.

Through on-board fishing vessel observations and Autonomous Underwater Vehicle (AUV) transects, this study explored the impact of trammel nets on cold-water gorgonian (soft coral) populations in the Northwestern Mediterranean Sea. High bycatch of gorgonians, especially larger colonies with greater than average height, was observed in the majority of assessed nets at an average rate of 2.4 ± 0.8 colonies or fragments per 200m of net. Impact was higher in specific areas below 80m depth and where wave heights were greater than 1m. Trammel nets mostly caught large colonies with greater height than average. Impact could be significantly mitigated by measures such as avoiding fishing at 80-90m depth during adverse weather conditions.

The authors worked with creel fishers to trial and assess whether sinking rope was practical to fish with in Scottish inshore waters, and therefore to reduce entanglement risk  to minke whales (Balaenoptera acutorostrata), humpback whales (Megaptera novaeangliae), basking sharks (Cetorhinus maximus), and other megafauna. Overall, the fishers reported few problems with the modified gear, and the gear performed well underwater according to Remotely Operated Vehicle (ROV) footage and sensors. Sinking rope may be a simple, viable option to reduce entanglement risk in the Scottish creel fishery.

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.
 

This study examined the effectiveness of various sizes of guarding nets to reduce bycatch (specifically crustaceans) in cuttlefish (Sepia officinalis) trammel net fisheries. All nets did significantly reduce crustacean capture, notably spider crabs (Maja sp.), but only the smaller mesh guarding net (20mm instead of 40mm) had no significant impact on target cuttlefish catch. However, guardnets may benefit fishers overall by avoiding later delays in disentangling bycatch and damage to gear. 

This study investigated 11 different longline hook sizes to increase catch of nemipterid fisheries  while reducing bycatch in the Phillippines. The largest hook demonstrated the lowest catch in count and weight, but did catch larger individual fish. Middle-sized hooks led to higher target catch, but also higher bycatch. The authors suggest that larger hooks would increase individual catch sizes and reduce bycatch, and that regulation of hook sizes is essential for for sustainable fishery management.