Seabirds are at greatest risk of becoming hooked and drowned when foraging during the short period between when hooks leave the vessel, and when they sink beyond seabirds’ diving ranges. Safe Leads are sliding weights that are used to increase the sink rate of baited hooks on branchlines in longline fisheries. By adding weight to the branchlines, baited hooks are placed out of the range of diving seabirds more quickly.
Safe Leads are an alternative to other line weighting devices such as leaded swivels, which, although effective at reducing seabird bycatch, pose a safety risk to fishermen as they are crimped tightly onto the monofilament line, and in the event of a line breakage, can fly-back and injure crew members. These safety concerns have led to development of Safe Leads. Safe Leads were developed by Fishtek Marine and BirdLife International and are designed to slide down/off the end of the line in the event of a line breakage, greatly reducing the energy of the recoiling line and likelihood of injury to fishermen.
As seen in the image below, Safe Leads are comprised of two lead halves which are sandwiched around the red rubber insert. The device is threaded onto the line and positioned by squeezing the sides of the rubber insert, temporarily releasing the device’s grip on the line and enabling it to be slid up and down.
On-shore trials of Safe Leads in Australia simulated bite-off/line breakage events and found that all weights successfully slid off the end of the line when placed within 2m of the hook. When positioned slightly further from the hook (3m) 80% of the weights slid off the end, and of those that didn’t slide off, they only hit “the vessel” with around 20% of the energy that a leaded swivel would hit with.
At-sea trials conducted in a South African tuna longline fishery reported only 4.2% of the Safe Lead fly-backs reaching the vessel (for comparison, 73.3% of leaded swivels reached the vessel), with the remainder falling in the sea.
An alternative version of Safe Leads, ‘Lumo Leads’, have since been developed by Fishtek Marine. These also work as a sliding weight, but are additionally encased in a luminescent nylon sheath that glows to attract bait fish.
This page was last updated on 12.02.21.
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