Bycatch Mitigation

Unintended catch of non-target organisms in fishing gear may be reduced by applying operational and technical mitigation measures. Operational measures include time/area regulations of fishing effort and gear use. Technical mitigation measures consist of modifications to fishing gear and practices. A number of technical bycatch mitigation means have been developed, experimentally tested, and implemented as part of regular fishing practices.

The highest number of mitigation techniques has been developed to reduce bycatch of seabirds in longline fisheries. The most effective mitigation measures include streamer lines, night setting, strategic offal discharge, line weighting, side setting, using dyed bait, and underwater setting chute. Switching to different bait, using dyed bait, and replacing conventional J hooks with circle hooks can reduce sea turtle mortality on longlines. Marine mammal bycatch in gillnets is reduced by using acoustic pingers, which warn animals about the fishing gear. Turtle excluder devices (TEDs) installed in the shrimp trawl, help turtles to escape from entering the trawl bag. Seabird collisions with industrial trawler warp cables could be minimized by deterring birds with streamer lines, therefore greatly increasing the visibility of cables extending from ship stern to the trawl.

However, bycatch mitigation solutions are not universal and differ among gears, fisheries, ocean region, and bycatch taxa. Therefore, nearly all fisheries have to test mitigation measures experimentally and figure out what works best in their fishing practices.  The following pages contain specific information about mitigation measures associated with the 4 major fishing gears that Project GloBAL is studying:

• Gillnet Bycatch Mitigation
  
• Longline Bycatch Mitigation
  
• Purse Seine Bycatch Mitigation
  
• Trawl Bycatch Mitigation