“Safe Leads” On Tuna Longliners Saves Birds And Sailor’s Heads ff

By Atuna.com

Seabird by-catch in tuna longline fisheries is a global conservation problem and one mitigation measure, in particular, has been the focus of research and innovation in recent years.

According to the Agreement on the Conservation of Albatrosses and Petrels, the most effective approach to reduce seabird mortalities is a combination of bird scaring lines, night setting and weighted branch-lines, but it’s this last measure that fishermen have grown reluctant to use because the traditional lead swivels have caused death or serious injury.

Traditionally, branch-lines are weighted with a lead swivel so the bait hooks sink faster and below the diving range of birds. The danger can occur in bite off events because the lead swivels are “crimped” to the line and part of the gear; if the line breaks due to too much tension, it can fly back towards the fishing vessel at speeds of 400 km/h and severely hurt crew members.

The U.K.-based company Fisktek Marine, in partnership with the bird conservation group, BirdLife International, believe they have designed a safer solution. A “Safe Lead” is threaded onto the line and held in place by silicon rubber rings which grip the line with 5 kg of tension. Because the weight is not part of the gear, the Safe Lead simply slides down the line or off the end depending on the distance from the hook, and the energy is dissipated, explains Ben Sullivan, coordinator of BirdLife’s Global Seabird Program.

“All the energy is lost and it just kind of lobs back at the boat rather than coming back like a bullet,” says Sullivan.

In at-sea trials in South Africa, only 4.2% of Safe Lead fly-backs reached the vessel (the remainder fell in the sea) whereas 73.3% of fly-backs by leaded swivels hit the vessel and one hit a crewman in the head, according to the “Safe Leads for Safe Heads” research report.

Safe Leads have only become commercially available in recent weeks, and Sullivan says there is already interest from Australia, New Zealand and South Africa.

While the technology only works on monofilament lines, fisheries that use wire traces can follow the lead of Japanese innovator and tuna fisherman, Kazuhiro Yamazaki. Last year, he won the World Wildlife Fund’s Smart Gear Competition for designing the ‘Yamazaki Double-Weight Branchline.” In this case, two leads are placed at either end of a 1-1.5 m section of wire and this configuration is inserted into a branch-line, two meters above the hook. The weight closest to the hook is free to slide, while the second is fixed into position. The double weight ultimately reduces the risk of injury to crewmembers by spreading out the mass.

Seventeen of 22 species of albatross are threatened with extinction and the majority of the 17 are killed in longline fisheries (including pelagic fisheries), says Sullivan. He says fisheries in the Atlantic Ocean are a “by-catch hotspot,” especially off the coast of Brazil and Uruguay.