Fishing Gear

    Longline, purse seine, gillnet, pole and line and troll fishing gears are employed in pelagic tuna and billfish fisheries. However, there is very little bycatch associated with pole and line fishing and there are very few commercial vessels trolling for tuna. For these reasons, the BMIS focuses on longline, purse seine and gillnet fishing gear.

    Read the International Seafood Sustainability Foundation 's (ISSF) overview of fishing methods used in tuna fisheries here.

    ISSF's assessment of the impact of different gear types on bycatch can be read here.

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    Longline

    Drifting longlines are used in pelagic fisheries targeting tuna and billfish. The longline, or mainline, is suspended horizontally at a pre-determined depth in the water column by buoy lines attached to regularly spaced surface floats.

    Gillnet

    Significant tuna fisheries utilise pelagic gillnets. Modern nets are typically constructed from synthetic fibres, such as monofilament nylon.The top edge of the net is attached to a rope called the headline, floatline or corkline. Floats are attached to the headline to provide buoyancy. The bottom edge of the net is usually attached by hanging twine to a rope called the footrope or leadline. Weights or sinkers made of lead or other materials are attached to the footrope and spread the net vertically in the water. The type and number of floats and weights used depend on whether the net is to be positively or negatively buoyant (FRDC).