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Summary: Longlines were set at depths greater than 100m using weighted lines to reduce bycatch of recreationally important fish species and protected species such as seabirds and sea turtles. While bigeye tuna catch rates were consistent between control and experimental sets, bycatch rates increased for sickle pomfret and opah but decreased for wahoo, dolphinfish, blue and striped marlin, and shortbill species. These species are generally not targeted but retained for their commercial value. Bycatch of sharks and pelagic stingrays did not differ between the experimental and control sets.

Summary:

Rare earth metals (made of cerium mischmetal) were compared with control treatments of standard circle hooks and inert steel above circle hooks on longline fishing gear to determine if bycatch reduction of spiny dogfish (Squalus acanthias) could be achieved. Results indicated a slight reduction in dogfish bycatch and a greater reduction in catch of longnose skate (Caliraja rhina) on hooks with mischmetal. Problems for using mischmetal commercially include its expense, hazardous nature, and rapid hydrolysis in seawater.

Summary:

The addition of a prototype "tunnel excluder" consisting of a filter grid (inclined at ca. 20 degrees) that leads to an escape tunnel in the Mauritanian industrial trawl fishery nets achieved a 40-100% reduction in bycatch of vulnerable species, including allowing 100% of rays and turtles to escape, 75% of manta rays, 40% of billfish and between 20-75% of sharks to escape. Cetaceans were less likely to use the tunnel to escape due to the narrowness of the design. 

Summary:

The catches from five experimental trawls (TED + fisheye BRD, upward facing TED, downward facing TED, bigeye BRD and square-mesh panel BRD) were compared to those of the standard twin Florida Flyer prawn trawl. Nets with a combination of a TED and BRD reduced sea turtle catches by 100%, large sponges by 85.3%, sharks by 36.3% and rays by 17.7% and reduced the proportion of soft and damaged prawns by 41.6% and catches of tiger prawns by 6.5%. Upward and downward facing TEDs reduced sea turtle bycatch by 99% and 100% respectively and large sponges by 81.6% and 95.9% respectively. Catches of tiger prawns (P. semisulcatus and P. esculentus) were reduced by 6.3% with the use of TEDs. The BRDs had little impact on the catch of either target or bycatch species.

Summary:

The type (circle 18/0 0 degree offset and J-style 9/0 10 degree offset) and position of hooks in the water column were tested to determine the effects on catch rates and mortality of elasmobranchs in pelagic and bottom longline fisheries in Brazil. Tests were conducted aboard pelagic and bottom longline vessels. Catch per unit effort (CPUE)  for blue shark (Prionace glauca), silky shark (Carcharhinus falciformis) and oceanic whitetip sharks (Carcharhinus longimanus) were significantly higher with circle hooks than with J-style hooks. Silky, blue and oceanic whitetip sharks had a significantly higher mortality at haulback with J-style hooks. Significant differences in hooking location between the two hook types was found for night, blue, silky and oceanic whitetip sharks. These sharks were more commonly hooked externally vs internally.  No significant differences between hook types was found for the CPUE of the sharks on bottom longlines.  Significantly more blacknose sharks (Carcharhinus acronotus) were alive at haulback when circle hooks were used on bottom longlines. Bottom longlines were also used to test for differences in CPUE by fishing depth.  Demersal hooks had significantly higher CPUEs than those suspended in the water column for blacknose sharks, nurse sharks (Ginglymostoma cirratum), and southern stingrays (Hypanus americanus).

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:

The addition of a prototype "tunnel excluder" consisting of a filter grid (inclined at ca. 20 degrees) that leads to an escape tunnel in the Mauritanian industrial trawl fishery nets achieved a 40-100% reduction in bycatch of vulnerable species, including allowing 100% of rays and turtles to escape, 75% of manta rays, 40% of billfish and between 20-75% of sharks to escape. Cetaceans were less likely to use the tunnel to escape due to the narrowness of the design. 

Summary:

Pelagic stingrays (Pteroplatytrygon violacea) are a common bycatch species in the Mediterranean pelagic longline swordfish (Xiphias gladius) fishery. Experimental trials took place in the central Mediterranean Sea from 2005 to 2007 to investigate the importance of bait size, presence and type of light attractors, and hook size and shape on pelagic stingrays. Bait size and light attractants did not have a significant effect on stingray catch rate. Larger J-hooks reduced the stingray capture rate. 16/0 circle hooks had a significantly lower number of stingrays captured than J-hooks, up to 80%

Summary:

The presence of permanent magnets on hook and line and inshore longline gear was tested for its ability to reduce the bycatch of sharks and rays.  Neodymium-iron-boron magnets were affixed to hook and line gear and barium-ferrite magnets were attached to longline gear.  Both types of fishing gear showed species specific responses but overall elasmobranch capture was significantly reduced when magnets were used. In the hook and line fishery catches of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) and smooth dogfish (Mustelus canis) were both significantly reduced when magnets were used but catches of spiny dogfish (Squalus acanthias) and clearnose skate (Rostroraja eglanteria) were not.  Similarly, in the longline fishery, blacktip sharks (Carcharhinus limbatus) and southern stingray (Hypanus americanus) catch rates were reduced but sandbar shark (Carcharhinus plumbeus) catch rates were not when magnets were used. There were no differences in the catch rates of several fish species, including Atlantic croaker (Micropogonias undulatus), oyster toadfish (Opsanus tau), black sea bass (Centropristis striata) and bluefish (Pomatomus saltatrix) when magnets were used.  

Summary:

The presence of permanent magnets on hook and line and inshore longline gear was tested for its ability to reduce the bycatch of sharks and rays.  Neodymium-iron-boron magnets were affixed to hook and line gear and barium-ferrite magnets were attached to longline gear.  Both types of fishing gear showed species specific responses but overall elasmobranch capture was significantly reduced when magnets were used. In the hook and line fishery catches of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) and smooth dogfish (Mustelus canis) were both significantly reduced when magnets were used but catches of spiny dogfish (Squalus acanthias) and clearnose skate (Rostroraja eglanteria) were not.  Similarly, in the longline fishery, blacktip sharks (Carcharhinus limbatus) and southern stingray (Hypanus americanus) catch rates were reduced but sandbar shark (Carcharhinus plumbeus) catch rates were not when magnets were used. There were no differences in the catch rates of several fish species, including Atlantic croaker (Micropogonias undulatus), oyster toadfish (Opsanus tau), black sea bass (Centropristis striata) and bluefish (Pomatomus saltatrix) when magnets were used.