FLD

About the Fighting Line Device (FLD)

What Is the FLD?

The Fighting Line Device (FLD) is a gear innovation developed by Hawaiʻi longline fishermen to safely handle large hooked animals and reduce injury to protected species. It is designed to work with the weighted branchlines already used in the deep-set longline fishery. Hawaii Longliners+1
When a large animal is hooked, the FLD is attached to a heavy-gauge line and slid down the branchline until it catches on the 45-gram weight near the hook. From there, crew can put controlled pressure on the gear to straighten or remove the hook and recover as much line as possible before releasing the animal. The device also helps reduce dangerous flybacks when weights or hooks snap back toward the crew. meetings.wcpfc.int

How the FLD Is Used on the Boat

During a protected species interaction:

  1.  The crew assesses the situation and prepares the FLD.
  2. The FLD is clipped to a strong leader line and slid down the branchline to the weight near the hooked animal. meetings.wcpfc.int
  3. Using the FLD, crew apply steady, controlled pressure to:
    ○ Help straighten the hook out of the animal’s mouth or body (especially for false killer whales), or
    ○ Safely control sharks and other large animals while retrieving as much gear as possible. Hawaii Longliners+1
  4. Once the animal is released and as much gear as practical is recovered, the line is brought back on board and fishing can resume.

This process is intended to keep both animals and crew safer during difficult interactions.

Why the FLD Matters

The FLD is an important tool in the Hawaiʻi deep-set longline fishery because it:

Improves animal welfare

Helps reduce injury and mortality for protected species such as false killer whales, other cetaceans, leatherback sea turtles, giant manta rays, and oceanic whitetip sharks.

Supports crew safety

The FLD is clipped to a strong leader line and slid down the branchline to the weight near the hooked animal. meetings.wcpfc.int

Protects gear and fishing efficiency

Allows fishermen to straighten hooks and recover more gear instead of cutting lines far from the animal. Hawaii Longliners+1

Helps the fishery stay sustainable

Contributes to NOAA’s protected species mitigation goals and supports long-term access to important tuna fishing grounds in the Pacific Islands Region.

The FLD Effectiveness Video Project

The FLD Effectiveness Video Project uses real-world videos from Hawaiʻi longline vessels to evaluate how well the FLD works during actual protected species interactions.
Through this project we aim to:
  • Collect at least 50 high-quality videos showing FLD use on priority species.
  •  Document deployment, handling techniques, and release outcomes.
  •  Analyze interactions to understand
    • How often FLD use leads to successful releases,
    • How injury and mortality may be reduced, and
    • How crews use the device across different vessels and situations.

The results will help NOAA Fisheries, the Hawaiʻi Longline Association, and vessel crews refine training, improve handling practices, and strengthen bycatch mitigation measures in the Pacific Islands Region