Grand Prize Winner 2011

This device is designed to reduce seabird bycatch in pelagic longline fisheries when used in combination with tori lines and in some cases night setting.  The double-weight configuration is designed to 1) sink pelagic longline hooks beyond the range of seabird attacks within the aerial extent of a tori line during line setting, and 2) reduce injuries to crew should a hook come free while under tension in the landing process and recoil back at the vessel.

The Yamazaki double-weight configuration consists of two leads placed at either end of a 1 to 1.5 m section of wire or wire trace. This weighted section is inserted into a branchline 2 meters above the hook. The weight nearest the hook is free to slide along the branchline while the second lead is fixed. The double weight reduces the danger of weight recoil injury by: 1) spreading the mass of the weights (two smaller weights are better than one) across the wire trace, 2) including a sliding weight that dampens the speed at which the weight can recoil; including a 1 to 1.5 meter section of stretch resistant line (wire) which serves to also reduce recoil energy; and positioning the larger of the two weights in or near the hands of a crewman as the fish is under maximum tension as it approaches the sea door.

The conservation potential of this device is substantial. Some countries have opposed branchline weighting for seabird conservation due to serious safety issues. The Yamazaki double-weight branchline is an innovation that meshes practicality and safety with function and conservation and breaks down the barriers to the adoption of branchline weighting as a seabird bycatch mitigation measures in world tuna commissions (RFMOs) and in domestic fisheries. Mechanistically weighting branchlines forces baited hooks to sink quickly to depths beyond the reach of seabirds within a distance that can be protected with bird-scaring lines.

Conservation Potential

Branchline weighting and bird scaring lines deployed properly are the one-two punch answer to seabird conservation in tuna longline fisheries. Used in combination with night setting seabird bycatch should can be reduced to the lowest level possible. This innovation also paved the way for the Agreement for the Conservation of Albatrosses and Petrels to endorse the simultaneous use of branchline weighting, bird-scaring lines and night fishing as best-practice seabird bycatch mitigation in pelagic longline fisheries. Trials with this device reduced seabird bycatch compared to un-weighted branchlines by 89% with no effect on fish catch rates.

It has the potential to spread this conservation success to the oceans of the world and allow tuna fisheries and albatrosses and petrels to coexist.