Smarter fishing gear: making fishing gear more selective
Smart Gear Competition
Bycatch mortalities can often be reduced by modifying fishing gear so that either fewer non-target species are caught or so the survival chances of captured non-target species are significantly improved. These modifications are often easy to implement and inexpensive.
Even simple changes to fishing practices, such as the time of day fishers set their gear, or the type of bait used, can significantly reduce bycatch.
Examples of more selective fishing gear include:
Turtle excluder devices (TEDs) for shrimp trawlers
TEDs are metal grids that allow shrimp to pass into the main part of the trawl net, but which allow marine turtles to escape with only a minimal reduction in shrimp catch.
Circle hooks for longlines
In many fisheries, the use of certain types of circle hooks instead of traditional J-shaped hooks on longlines can significantly reduce marine turtle deaths without adversely affecting commercial catch rates.
Deeper setting of longlines
Bycatch of marine turtles, sharks, and non-target fish in tuna and swordfish longline fisheries can be reduced through a simple modification that allows the baited hooks on longlines to fish at depths below 100m – the depth where most target fish, but fewer bycatch species, are found.
Escape Panels
The mesh in trawl nets is often tied into a diamond shaped configuration. As more fish are caught and the weight in the trawl net increases, these diamond shaped meshes stretch and the opening therefore narrows – preventing the escape of juvenile/small fish. Square meshes, on the other hand, retain their shape when under weight and by simply inserting a square mesh panel into a trawl net this allows considerably more juvenile/small fish to escape.
Bird scaring devices
Seabirds can die when they hit the ropes that attach fishing gear to the fishing vessel. They accidentally hit the ropes because they are attracted to both the baited longline hooks after deployment from the vessel, and also from discharges of fish waste resulting from on-board processing. Streamer (tori) lines attached near these ropes are extremely effective at preventing birds from striking these ropes. They consist of lines with brightly coloured tubing or ‘streamers’ which flap about unpredictably in the wind. They also deter birds from foraging near bait/offal discharges. A number of other ideas based on this principal are also effective at preventing seabirds mortalities
Pingers
These electro-acoustic devices are attached to gill nets and emit an acoustic signal which alert cetaceans to the presence of the net and therefore minimizes entanglements.
