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The study compared the catch efficiency and impacts on chondrichthyan bycatch between monofilament and multifilament trammel nets in small-scale fisheries along the coast of Çanakkale, Türkiye. Multifilament trammel nets caught 1.22 times more target species (species with economic value) than monofilament trammel nets. Monofilament nets also had a higher catch rate of non-target (discard) species, including higher catch of species listed on the IUCN Red List as vulnerable, endangered, or data-deficient. 

Between 2019 and 2022, trials using three different pinger models (Future Oceans 10 kHz, Future Oceans 70 kHz, and PAL Wideband) were conducted in Bulgaria during standard turbot fishing operations. Marine mammal bycatch was observed in  61% of all hauls. No significant difference in bycatch rates between active and control nets was observed in trials involving Future Oceans 10 kHz (17 trials) and 70 kHz (6 trials) pingers. However, a significant reduction (74%) in cetacean bycatch was recorded during the trials conducted with PAL Wideband pingers. 

Most bycatch studies focus on technical changes and compare a modified gear or fishing method to the traditional gear and method under experimental conditions. Relatively few studies have been able to track the actual reduction achieved if there is fleetwide implementation of the change.  Modifications to fishing gear and methods emerges as by far the most effective for ETP species, with observed reductions from 40% to nearly 100% in actual fishery case studies. However, with some exceptions, gear modification has not been widely implemented in fishing fleets and evaluated estimates of their effectiveness are based on what is not caught, usually without accounting for post-release mortality resulting from gear-related injuries. In addition, to evaluate fleetwide effectiveness, a very high rate of observer or electronic monitoring would be required and there are relatively few fisheries in the world where such conditions are met. 

Gear and fishing method changes, followed by dynamic area management, are the most effective approaches for bycatch reduction and probably the most well accepted by fishers. They are already implemented in many parts of the world and managers can learn from those case studies on how to implement and enforce these mitigation measures. Permanently closed areas appear to be less effective than closed areas that move with changing fish distribution but do require either intensive real-time monitoring or reliable predictive monitoring. However, if the dominant bycatch concern is a single species, then closed areas targeting the areas of high bycatch can be effective. 

Time-depth recorders paired with geolocation sensors or GPS loggers in Aotearoa, New Zealand were used to quantify the diving ecology of three Procellaria petrel species. All three species dove faster than the current best-practice longline sink rate of 0.5 meters/second, highlighting that the risk of interaction with these species is still present. There were also significant differences in diving behavior among and within species, including diurnal trends, sex-specific differences, and for black (P. parkinsoni) and Westland petrels (P. westlandica), changes in diving behavior across the breeding period. These results highlight the necessity of ensuring that bycatch mitigation methods take the strong diving capabilities of these three species into account. This includes night setting when many seabirds are less active and when dives are shallower, use of tori lines for smaller vessels, and a 20m threshold for hook-shielding or bait-setting devices (or combining these devices with bird-scaring devices and/or additional weighted branch lines to protect hooks to 20m). Furthermore, it can be beneficial for custom/target-specific bycatch mitigation methods being developed to take into account the necessary ecological context. 

This study tested whether a zinc/graphite galvanic electric field reduced capture of elasmobranchs in demersal and pelagic longline fisheries in Florida and Massachusetts (United States). The catch per unit effort of demersal sharks in Florida using the zinc/graphite treatment was significantly lower than the controls, with a 62.3-69.5% reduction in sharks caught on the zinc/graphite treatment. However, there was no difference in  demersal shark CPUE between treatments in Massachusetts. Too few sharks were captured in the pelagic longline trials to allow statistical comparison; however, capture of targeted bony fishes was greatest on hooks with the zinc/graphite treatment, suggesting no negative effect on target catch rates.  Additionally, there was an observed difference in efficacy of the zinc/graphite between Carcharhiniform sharks (more effective) and the Squaliform sharks (less effective), which suggests that the response to this deterrent may be species-specific. Further testing is needed to understand the limitations of the gear and efficacy for pelagic species. 

This study assessed the catch and environmental outcomes of modified scallop dredge designs aimed at reducing environmental impact without changing catch efficiency. Four gear designs were tested: N-Viro dredge with conventional belly bag, N-Viro dredge with skid belly bag, Newhaven dredge with skid belly bag, and the standard Newhaven dredge with conventional belly bag (control). Results showed that the N-Viro dredge alone did not increase catches of market-sized king scallops (Pecten maximus); however, pairing it with a skid belly bag improved catches by 14%–19%. The N-Viro dredge reduced undersized scallop catch by 42% and stones by 67%, with further reductions when combined with a skid belly bag. The N-Viro dredge also decreased fuel consumption by about 30%, while the skid belly bag reduced gear footprint by about 55%. Biomass of bycatch was higher for stonier habitats irrespective of the dredge used, however, skid belly bags caught more bycatch than standard belly bags, and this difference was more pronounced when an N-Viro dredge was also used. 

This study tested the efficacy of a modified trawl net in the brown shrimp (P. californiensis) fishery in northern Peru. The modified net was designed to improve selectivity by incorporating 60 mm, 50 mm, and 36 mm mesh sizes, modifications to the net mouth were made to achieve a more pronounced catenary curvature, and the net was constructed primarily from polyethylene in various sections to reduce its overall weight. To further enhance selectivity, an additional footrope was incorporated to facilitate the exclusion of certain benthic species, such as soles, starfish, and other bottom-dwelling organisms. A square mesh window was added 60 cm from the bottom center of the net mouth to allow the escape of snails and crabs. The modified net reduced bycatch by 35% and discards by 50%, while the catch of target species remained unchanged. The reduction in bycatch was not significantly different for species of fish, although catch of this species group was reduced by 24%.