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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 could be achieved. Results indicated a slight reduction in dogfish bycatch and a greater reduction in catch of longnose skate on hooks with mischmetal. Problems for using mischmetal commercially include its expense, hazardous nature, and rapid hydrolysis in seawater.

Summary:

The effect of circle hooks and J-style hooks on the catch composition, catch rates, hooking location and status of release of target and bycatch species were compared on pelagic longline vessels.  There were significant differences in catch rates between the two hook types for bigeye tuna, which had higher catch rates on circle hooks and sailfish, pelagic stingrays, and leatherback sea turtles, which had higher catch rates on J-style hooks.  Survival of bigeye and yellowfin tunas was significantly higher when circle hooks were used and bigeye and yellowfin tunas, swordfish and sailfish had significantly higher external hookings when circle hooks were used.  The results suggests using 18/0 circle hooks with a zero degree offset could increase the survival of bycatch species while having minimal effects on the catches of target species.

Summary:

The effect of circle hooks and J-style hooks on the catch composition, catch rates, hooking location and status of release of target and bycatch species were compared on pelagic longline vessels.  There were significant differences in catch rates between the two hook types for bigeye tuna, which had higher catch rates on circle hooks and sailfish, pelagic stingrays, and leatherback sea turtles, which had higher catch rates on J-style hooks.  Survival of bigeye and yellowfin tunas was significantly higher when circle hooks were used and bigeye and yellowfin tunas, swordfish and sailfish had significantly higher external hookings when circle hooks were used.  The results suggests using 18/0 circle hooks with a zero degree offset could increase the survival of bycatch species while having minimal effects on the catches of target 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:

Pelagic stingrays (Pteroplatytrygon violacea) are a common bycatch species in the Mediterranean pelagic longline swordfish 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:

Pelagic stingrays (Pteroplatytrygon violacea) are a common bycatch species in the Mediterranean pelagic longline swordfish 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:

A study was conducted to determine the impact of removing the 'tickler' from in front of groundgear of trawls. The 'tickler' is a length of chain placed in front of the groundgear of trawl gear, which is supposed to increase catches of sharks and rays. Tests were conducted where the 'tickler' was removed and secondary nets (groundgear bags) were placed behind the groundgear to determine the amount and species of fish that escaped capture. The results indicated that removing the 'tickler' from in front of the groundgear reduced the capture of skates and sharks. Therefore, prohibiting the use of 'tickler' chains in critical habitats for skates and sharks could be a beneficial management tool.

Summary:

This study tests the impact of skids placed on scallop dredges in various habitats to reduce seabed impact; skids raise the scallop collecting bag 10-11cm off the seabed. The modified skid dredge caught more marketable scallops per unit area, but also retained more bycatch overall and more undersize scallops. Results were habitat specific.

Summary:

A mobuilid sorting grid placed over the hopper used to sort bycatch on tuna purse seine vessels aided in the release of larger mobuilid rays without increasing handling time.  

Summary:

Elasmobranch bycatch significantly decreased in bottom-set gillnets in the Gulf of California using orange LEDs, ultraviolet LEDs, green LEDs, and green glow sticks, with orange LEDs being the most effective at reducing bycatch. As a whole, catch of bony fish was not affected by illumination, although responses were taxonomic-specific.