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Guarding nets may potentially help mitigate bycatch in trammel net fisheries through the attachment of a supplementary netting panel, typically 10–30 cm high and made of materials that resist entanglement, between the footrope and the main trammel net. Acting as a physical barrier, the panel prevents benthic organisms from becoming trapped. In a small-scale prawn trammel net fishery in Thailand, biomass of non-target organisms was significantly reduced while maintaining target species volume compared with conventional nets. However, the volume of commercial bycatch species was also significantly reduced, which may create a barrier to adoption in small-scale fisheries.  

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%. 

This study tested the use of different types of fishing gears to compare their effectiveness in catching the invasive blue crab (Callinectes sapidus) in the Northern Adriatic Sea. The tested gears included traditional fyke nets and four types of crab pots with either single or double chambers. Results indicated that both the double chamber pot and fyke nets were most effective gears overall in terms of catch efficiency and yield (catch per unit effort). However, the double chamber pot had significantly higher species selectivity, with lower bycatch of the native green crab (Carcinus aestuarii), as well as greater size selectivity (targeting larger adults). 

Understanding the behavior of snow crab in response to escape gaps is important as it may impact escape success, including the number of attempts, as well as time taken to escape successfully. The study filmed movements of snow crabs through different sized and shaped escape gaps in a laboratory setting and compared movement patterns with those of pot netting mesh. The results showed that escape success strongly depends on crab orientation, the time required to escape a trap can be reduced when using escape gaps, and escape gap design strongly influences size selectivity. In addition, escape probability decreases with crab size. Specifically, circular gaps can retain target-sized crabs while releasing undersized crabs, while elongated or wide gaps increase the risk that target-sized crabs escape. Additionally, side-by-side gaps or mesh can cause limb entanglement and delayed escape.

Studies were conducted aboard beam trawlers in the North Sea to determine the performance of pulse beam compared to conventional tickler chain beam trawlers.  Overall the pulse beam trawl caught 68% less than the conventional trawls.  Specifically, the pulse beam trawl caught significantly fewer plaice (Pleuronectes platessa) and sole (Solea vulgaris) compared to the conventional beam trawl. There was no significant difference in catch rates of undersized plaice between the two gears but the pulse beam trawl caught significantly less undersized sole.  Pulse beam trawls caught more turbot (Psetta maxima) and brill (Scophthalmus rhombus) (78%-131%) than conventional trawls but fewer cod  (Gadus morhua) (15%-60%).  In addition, catch rates of bottom species, including sandstar (Astropecten irregularis), common starfish (Asterias rubens) and swimming crabs (Liocarcinus holsatus), were significantly less when the pulse beam trawl was used.

This study examined demersal trawl gear used to catch Greenland halibut (Reinhardtius hippoglossoides) in west Greenland. A towed video sled recorded trawling impacts on seafloor fauna. Trawling effort was significantly linked with community composition, with a negative association between trawling effort and abundance of some taxa, including some vulnerable marine ecosystem (VME) indicators, as well as regionally rare species (Balticina finmarchica).

This study compared the selectivity of two sorting grids (G1-SM40 and G20-ST20) and a T90 codend to a control trawl in a commercial bottom trawl fishery  targeting deep-water rose shrimp (Parapenaeus longirostris) and European hake (Merluccius merluccius) in the central Mediterranean. All modified gears reduced catches of undersized shrimp and hake. The sorting grids improved target-species selectivity and reduced benthic discards relative to the control, and the T90 codend substantially reduced elasmobranch bycatch, particularly juveniles. Economic assessments showed that, although catch rates and revenues declined slightly, discard ratios decreased and selectivity improved, indicating a more sustainable exploitation pattern. Fuel consumption remained unchanged among gears, demonstrating that these modifications do not affect vessel energy performance.