One of the terms and conditions in the shallow-set fishery BiOp requires NMFS to conduct a workshop with fishermen, observers, relevant experts and NMFS’ Protected Resources Division staff to “determine whether there are more effective methods for removing more fishing gear from leatherbacks to increase their chance of survival after interacting with longline gear. … This workshop should be repeated as necessary and findings should be incorporated into the annual Protected Species Workshops given by NMFS [Sustainable Fisheries Division].”
The opinion cites an estimate from Wespac’s Asuka Ishizaki that leatherback deaths could have been reduced by about 20 percent from 2004-2018 by reducing trailing gear.
“Identifying and incorporating such measures through the workshop may help to reduce the adverse effects of fishery interactions with leatherback sea turtles,” it stated.
Enter Caleb McMahan, former federal fishery observer and current media and marketing director of Hawaiian Fresh Seafood. For the past few years, he has been spearheading a local effort to develop a device that can slide down the branch lines of longline gear, and then clip the lines as close as possible to incidentally caught animals. Conceivably, it could even remove the hook as well, he said in an interview.
His current iteration, which is still being developed in cooperation with Makai Engineering, builds on a design he developed with a machinist from Mapunapuna. That design itself was based on a prototype developed with federal grant funding on the East Coast.
In testing his first device, a clunky stainless steel contraption that cost $3,000 to make, he found it was able to release hooked blue sharks with only a few inches of line remaining. With satellite tags provided by Melanie Hutchinson, a bycatch researcher with the Pacific Islands Fisheries Science Center, he was able to see that the sharks survived more than 30 days after being released.
Earlier this year, McMahan received grant funding that allowed him to work with Makai Engineering to improve the device.
“The new generation of the concept blows the other one out of the water. We’re talking about a piece of equipment now much more capable of doing the job,” he said.
“We have designs of a line-cutting device capable of cutting through the hook, the wire, and the leader. This thing can crawl down the line in case of an obstruction or sag. You can put a camera on this thing,” he continued. It looks a little like a football, with the moving parts encased inside.
If McMahan wins enough grant funding to complete a successful prototype, he said vessels could conceivably start using the device within one year.
He said the device will definitely work best with an animal hooked onto a single line and not entangled with any other gear. While it could apply to false killer whales, which can be hooked by longline vessels targeting bigeye tuna, McMahan said mitigation for that species has focused mainly on ways to get the whales to free themselves.
Some people involved in mitigation discussions for that species “don’t even want to look at trailing gear,” he said.
For now, the device is being considered primarily as a way to minimize trailing gear on sea turtles, especially those hooked by the Hawai‘i swordfish fishery. He said he’s also awaiting grant funding to work with the same engineering company on designing satellite tags so that the device can deploy them on leatherback turtles.
Earthjustice attorney David Henkin told Environment Hawai‘i, “If such a device could minimize harm, that would, of course, be wonderful, but I’m not getting my hopes up until it proves itself in action.”
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