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Summary: An experimental trawl net fitted with a 120 mm square-mesh escape panel was tested against the standard trawl net of the Irish Sea Nephrops fishery. The experimental net allowed 54% of juvenile haddock and 65% of juvenile whiting to escape, and there was no loss in catches of the targeted Nephrops.

Summary: A semi-flexible exclusion grid with a bar spacing of 15.5 cm reduced dolphin bycatch in the Pilbara trawl fishery by close to 50% and reduced the bycatch of sea turtles, large sharks and rays. However, the fate of the dolphins that encountered the grid and escaped is unknown.

Summary: A semi-flexible exclusion grid with a bar spacing of 15.5 cm reduced dolphin bycatch in the Pilbara trawl fishery by close to 50% and reduced the bycatch of sea turtles, large sharks and rays. However, the fate of the dolphins that encountered the grid and escaped is unknown.

Summary: Gillnets from the North Sea wreck net fishery equipped with pingers, had a 100% reduction in the bycatch of harbour porpoises, compared to nets with no pingers attached.

Summary: Crab traps were fitted with a Turtle Excluder device to reduce the incidental capture of diamondback terrapins. No diamondback terrapins were caught during this study but the total catch rate of targeted blue crabs, compared to the standard traps, increased by 25.7% (14.5% sublegal size, 32.9% legal size). The difference in total catch rates and catch rates of legal sized blue crabs between the two traps were significantly different.

Summary:

Bottom set gillnets with pingers (LU-1, 8 signals, 145 dB, 300 ms, random signal intervals) attached were tested against standard nets and nets with dummy pingers (double blind) to determine if they could reduce the incidental capture of harbour porpoises. The proportion (number of nets with porpoises/number without) of harbour porpoise bycatch was reduced from 0.00229 and 0.00295 for nets with dummy pingers and no pingers respectively, to 0.00015 for nets with active pingers. The difference in bycatch rates between nets with active and dummy pingers was statistically significant but not between nets with dummy pingers and with no pingers.

Summary:

Several versions of a terrapin excluder design were tested on crab traps to determine how effective they were in reducing terrapin bycatch and what the effect on catch rates of targeted crabs was. All tests consisted of modified and unmodified traps being set in an alternate fashion. A wire bar placed across the opening of the traps was unsuccessful in reducing terrapin bycatch. A second design, which was a rectangular frame (5x10 cm) was successful. Standard traps caught 13 out of 15 terrapins during 1992 and 46 out of 51 during 1995, with the remainder of terrapins being caught by traps modified with the frame. Additional testing of the rectangular frame size, determined the 4.5x10 cm frame reduced terrapin bycatch the most (22 terrapins caught in unmodified vs. none in modified traps). Additionally, crab catch rates were 9% higher in the modified traps (4.5x10 cm) compared to the unmodified traps and crabs were of similar sizes in the two traps. In comparison, crab catch rates were 11% higher than in the unmodified traps when the 5x10 cm excluder design was used in 1994 (multiple sites) and 49% higher in 1995 (single site).

Summary:

Codends modified with rectangular mesh panels (one oriented length-wise in the cod end and one oriented width-wise, each measuring 7 x 11 bars) reduced the weight of discarded bycatch by 46% and 38% respectively but did not significantly reduce the catch of targeted prawns. A haulback delay of 10-15 seconds allowed juvenile red spot to escape through the square mesh panels, while trawls with no delay showed no significant reduction in the bycatch of this species.

Summary:

The addition of a filter grid (inclined at ca. 20 degrees) that leads to an escape tunnel in trawl nets allowed 100% of rays and turtles to escape, 75% of manta rays, 40% of billfish and between 20-75% of sharks to escape.

Summary:

The addition of a filter grid (inclined at ca. 20 degrees) that leads to an escape tunnel in trawl nets allowed 100% of rays and turtles to escape, 75% of manta rays, 40% of billfish and between 20-75% of sharks to escape.