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Kaua‘i and Big Island fishermen to trial new tuna tagging technology

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It’s summertime in Hawai‘i: ‘Ahi season, when Pacific yellowfin tuna traditionally run at their greatest numbers in island waters.

A cadre of Kaua‘i and Big Island fishermen are set this year to do more than simply catch ‘ahi – an iconic, torpedolike tuna important to local culture and cuisine. They will trial first-of-their-kind tags intended to change how fish are studied.

A Kona boat captained by Nathan Abe with PIFG personnel – including Clay Tam and PIFG videographer Dean Sensui – aboard in 2016. Photo Courtesy: Molly Lutcavage

Lifelong Kaua‘i fisherman Cory Nakamura has caught at least one ‘ahi per year since first stepping foot on a boat at the age of 5. He is participating because he wants to ensure future generations can grow up doing the same.

“We would like to continue this culture and lifestyle … We always celebrate having some fresh fish around,” said Nakamura, the principal of Elsie H. Wilcox Elementary in Līhu‘e, who worked as a part-time commercial fisherman during his early teaching days. “It’s going to take some science and some good habits to sustain the availability of fish in the future.”

The Hawai‘i ‘ahi fishery is neither overfished nor subject to overfishing, according to NOAA Fisheries. But there is much to learn about the species in Hawai‘i waters. Its annual migration routes, spawning grounds and connectivity to tuna elsewhere in the Pacific are not well documented.

Marine scientists with the University of Massachusetts Boston-affiliated Large Pelagics Research Center and the nonprofit Pacific Islands Fisheries Group in Hawai‘i have spent the past nine years with help from collaborators developing HI Tag. The new system relies on fishermen’s smartphones to collect data on tagged fish that they tag and release, like ‘ahi.

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Hawai‘i fishermen have long participated in tag-and-release studies on bottomfish led by PIFG researcher Clay Tam. Those relationships led to the first successful HI Tag trials with Kona fishermen on the Big Island in 2016.

Each HI Tag is a small strip of plastic, or ID tag, with an RFID chip embedded inside. A dart on one end allows participating fishermen to easily attach the tags to fish using a tag applicator reminiscent of an awl.

When a fish carrying a HI Tag is recaptured, printed information on the tag will prompt fishermen to scan it with their smartphone. Doing so will transmit data, including the fish’s tag number and location, to a secure database in the cloud.

HI Tags cost an estimated $5 each, making them more expensive than conventional “spaghetti” ID tags, which cost up to $3 each and are nothing more than small plastic streamers with printed identification and contact numbers.

That difference adds up when buying in bulk, but HI Tag’s developers think the increased cost is worth it, given improved data quality and time and effort saved in the laboratory. Fishermen who catch a conventionally tagged fish must have the time – and the inclination – to remove the tag, fill out a data form and mail it to the appropriate scientist.

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“To report a conventional tag recapture, the tag usually needs to be physically removed. The printed ID and contact information is tiny, so most fishermen have to land the fish to recover the tag information. That ends the tag’s journey,” said Hong Kong-based scientist and HI Tag developer Tim Lam.

From left: Fishermen prepare to tag an Atlantic bluefin tuna, while a freshly-tagged ahi is released into the Pacific. Pop-up tags were used in both cases. Photos Courtesy: Molly Lutcavage & Kevin De Silva

“In the case of rewards, tagging programs also usually require a ‘proof’ of recovery from the reporting fisherman via the physical tag in order to receive a reward,” Lam continued. “However, by scanning a HI Tag, the tag ID can be transmitted from the tag to a phone or separate reader, so the tag can remain on the fish, ready for future recapture events.”

Lam believes HI Tags will change how conventional tagging has been done over the past 50-plus years.

“We want to turn a ‘single-use’ tool into ‘multiple-uses’ and by doing so, have the potential to trace different snapshots of a fish’s life through interactions with different fishermen – where more and more practice tag-and-release,” Lam said. “All fishermen will need to do is scan the tag and safely return the fish to the water. Then, valuable information will live through the modern web of things, keeping a continuous record of any interactions on the high seas. With such capability, we can start clocking in and clocking out a fish through its life history.”

Lam’s HI Tag partner is Molly Lutcavage, a longtime tuna researcher who splits her time between Gloucester, Massachusetts and Lāwaʻi on the Garden Isle. In February she organized a local visit from Capt. Dave Marciano of the National Geographic reality television series “Wicked Tuna,” who took time to promote scientific collaboration among the Kaua‘i fishing community.

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More recently, Lutcavage was one of two local marine biologists to help identify a mysterious creature found in the stomach of a Kaua‘i-caught ‘ahi.

“We think this cooperative research is, more than anything, a story about people being connected across the seas through their own unique commitments to tuna, either as fishermen, volunteer taggers, the scientists in our research communication chain, and of course, the fish itself. Our research focus has taken on the status quo of fish tagging,” she said of the HI Tag program. “Fishermen are really motivated and jazzed by tuna recapture stories we post on our Facebook page. And, Kaua‘i and our original Kona fishermen partners are psyched to trial new tags.”

HI Tag has been a labor of love for participating fishermen and scientists alike, since the program’s initial funding – less than $50,000 in grants and donations – was spent, mostly on field trials and related expenses.

To the best of Lutcavage’s knowledge, HI Tag is the first initiative to develop a smartphone app to aid in tracking tagged fish, although tagging is a fundamental practice known to reveal fascinating discoveries. Using $4,000 pop-up satellite archival tags, Lutcavage, Lam and collaborators demonstrated ‘ahi travel surprisingly great distances throughout the Pacific Ocean. Their findings were published in a 2020 research paper, the first of PIFG’s tuna and billfish studies.

An illustration of a HI Tag. Photo Courtesy: Molly Lutcavage

Lam, Lutcavage and fishermen on the East Coast also used pop-up and conventional tags to track the travels of a bluefin tuna named Amelia for 14 years. First caught off Rhode Island Sound at a mere 10 pounds, she was ultimately harvested off Portugal at 640 pounds and 93 inches long. (Click here to view a LPRC slideshow documenting Amelia’s life journey.)

“‘Ahi has always been a big part of eating fish in Hawai‘i, especially with the Asian culture that has migrated to Hawai‘i,” said Kaua‘i fisherman and chef Mark Oyama, of the popular restaurant Mark’s Place in Puhi on Kaua‘i. “It’s always there when you have special celebrations: New Year’s, Christmas, all those times you always have fresh ‘ahi.”

Oyama, a longtime collaborator of Lutcavage’s, is excited to troubleshoot the trial HI Tags: “It’s important to have this data and I think with these tagging programs, it’s the only way to get true data.”

Kristy Kahananui, a fisherwoman and owner and operator of Lawai‘a Fish Co. in Līhu‘e on Kaua‘i, is also eager to participate.

“Who doesn’t want to tag something and be able to follow it … and actually see where they go, what they do,” she said. “I think it’s pretty cool. Even their growth rate, I find everything so interesting.”

According to Kahananui, it may be summertime, but the ‘ahi are not running as they should be.

“Everybody anticipates summer coming, and for the last two or three years, it just hasn’t come: The ‘ahi bite,” she said. “This year they have just started biting but it’s not the same. It’s not like when I was a kid: We’d go out for one day and we could have 30 pieces of ‘ahi.

“Now my brother goes out there for three days and he’s lucky if he gets two or five. It’s just different.”

Scott Yunker
Scott Yunker is a journalist living on Kauaʻi. His work for community newspapers has earned him awards and inclusion in the 2020 anthology "Corona City: Voices from an Epicenter."
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