Hawaii’s deep-set longline fishery could see changes in the way it handles interactions with seabirds after recent field trials showed fishing pole-like “tori lines” are effective at keeping the birds away from fishing gear and bait.
Since about 2015 the interactions between seabirds, namely black-footed albatrosses and Laysan albatrosses, and fishing vessels and gear have gradually increased. Getting hooked can be fatal to the birds, so researchers and fisheries managers have been considering new ways to keep them away from vessels.
Promising data has revealed the use of tori lines, which are set up similarly to fishing poles and lines and are cast from fishing vessels, is more effective at deterring seabirds than the methods currently being used. 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 to create obstacles the birds must cross to get to baited hooks meant for fish.
Between February and June, researchers tested the 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 hooked on fishing gear when tori lines were employed. The birds were also four times less likely to make contact with fishing gear and 1.5 times less likely to even make an attempt at hooked bait.
It’s the second field trial studying the use of tori lines; a similar study was performed in 2020.
“It’s basically like a scarecrow tactic with the streamers flapping around,” said Asuka Ishizaki, the protected species coordinator for the Western Pacific Regional Fishery Management Council and part of the team that performed the study.
“The birds that we’re dealing with are two albatross species. … If you see them flying around, you don’t see them swooping or making sharp turns because they’re big and are made to glide in the wind. So they’re not going to come close to any structure that they can’t quickly turn away from. So it’s enough to keep them away.”
Since 2001, when the National Marine Fisheries Service first implemented rules requiring Hawaii’s longline fishers to try to deter the albatrosses, crews have usually done so by using thawed bait dyed with blue food coloring. It’s not clear why the seabirds are less attracted to blue-colored bait but it might be because they can’t spot it in the ocean or just don’t consider it food.
But with the recent increase in their interactions with fishing vessels, it appears the dye is becoming less effective. Officials said oceanographic changes also could be contributing to the increase in interactions.
On Wednesday, data from the field trial was presented to the fishery council, one of the central management bodies for fisheries in the Western Pacific region. Council members expressed an initial preference to ban use of blue-dyed bait by replacing it with tori lines.
Both of the albatross species that interact with deep-set longline fishing crews forage in the north Pacific Ocean and nest primarily in the Northwest Hawaiian Islands. Human development, hunting and fatal interactions with fishing vessels threatened their populations during most of the 20th century. Awareness and conservation efforts grew in the 1990s and led to interaction mitigation measures, including those being used in Hawaii.
Switching to tori lines also could be an appealing option for fishers, who reportedly find the preparation and use of blue-dyed bait “messy” and cumbersome and would rather use the tori lines.
“It’s not necessarily expensive, but it can be impractical handling the bait and the dye. And essentially it doesn’t work all that great either,” said Eric Kingma, executive director for the Hawaii Longline Association.
He’s confident fishers will like the tori lines better, especially if it doesn’t come at a cost. He also suggested the council consider allowing some flexibility in situations where a tori line breaks while a vessel is out at sea.
The council may call a final vote on the issue in December, with any recommendations sent to the U.S. Commerce secretary for approval and implementation by the National Marine Fisheries Service.
