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Hawaii’s deep longline fishery could see changes in the way it handles interactions with seabirds after recent field trials showed rod-like ‘tori lines’ are effective in keeping birds away from fishing gear and bait.
Since around 2015, interactions between seabirds, namely black-footed albatrosses and Laysan’s albatrosses, and fishing vessels and gear have gradually increased. Clinging can be fatal for birds, which is why researchers and fisheries managers have considered new ways to keep them away from vessels.
Promising data has revealed that the use of tori lines, which are set up the same way as fishing rods and lines and are cast from fishing boats, is more effective in deterring seabirds than methods currently in use. The streamers attached to the tori lines flap in the wind and are designed to scare away hungry seabirds. The lines are cast in such a way that there are obstacles that the birds must overcome to access the baited hooks intended for the fish.
Between February and June, researchers tested tori lines against the use of blue-dyed bait, which most fishing crews currently use. They found that seabirds were 14 times less likely to get caught or snag on fishing gear when tori lines were used. Birds were also four times less likely to come into contact with fishing gear and 1.5 times less likely to even attempt to catch a hook bait.
This is the second field trial investigating the use of tori lines; a similar study was carried out in 2020.
“It’s basically like a scarecrow tactic with the banners flapping,” said Asuka Ishizaki, protected species coordinator for the Western Pacific Regional Fisheries Management Board and member of the study team. .
“The birds we are dealing with are two species of albatross. … If you see them flying, you don’t see them diving or making sharp turns because they are big and are made to hover in the wind. So they are not going to approach a structure that they cannot quickly turn away from. So just keep them away.
Since 2001, when the National Marine Fisheries Service first put in place rules requiring Hawaiian longline fishermen to try and deter albatrosses, crews have typically done so using thawed bait dyed with blue food coloring. It’s unclear why seabirds are less attracted to blue-colored baits, but this may be because they can’t spot them in the ocean or just don’t view them as food. .
But with the recent increase in their interactions with fishing vessels, it seems that the dye is less and less effective. Officials said oceanographic changes could also be contributing to increased interactions.
On Wednesday, data from the field test was presented to the Fisheries Council, one of the central fisheries management bodies in the Western Pacific region. Council members expressed an initial preference to ban the use of blue-dyed baits by replacing them with tori lines.
The two albatross species that interact with deep-sea longline fishing teams feed in the North Pacific Ocean and nest primarily in the Northwestern Hawaiian Islands. Human development, hunting, and deadly interactions with fishing boats threatened their populations for much of the 20th century. Awareness and conservation efforts intensified in the 1990s and led to interaction mitigation measures, including those used in Hawaii.
Switching to tori lines might also be an attractive option for anglers, who would find the preparation and use of blue-dyed bait “messy” and cumbersome and would prefer to use tori lines.
“It’s not necessarily expensive, but it can be difficult to handle the bait and dye. And basically it doesn’t work very well either, ”said Eric Kingma, executive director of the Hawaii Longline Association.
He is convinced that anglers will like tori lines better, especially if it comes at no cost. He also suggested that the council consider allowing some flexibility in situations where a tori line breaks while a ship is at sea.
The board can call a final vote on the matter in December, with all recommendations sent to the US Secretary of Commerce for approval and implementation by the National Marine Fisheries Service.