University of Hawaiʻi researchers have published a new study that brings together ʻike Hawaiʻi (Hawaiian knowledge), ʻōlelo Hawaiʻi (Hawaiian language) and western marine science to shed new light on one of the ocean's most elusive predators, the cookiecutter shark.
Rarely seen but often noticed, the cookiecutter shark is named for the distinctive wounds it leaves behind. Instead of tearing flesh, the small shark removes neat, circular plugs of meat that resemble the cut of a cookie cutter. These unmistakable bite marks are commonly found on prized fish such as ʻahi (bigeye tuna) and aʻu kū (swordfish), providing scientists with rare clues about the shark's behavior in the deep, open ocean.
"What makes this species so fascinating is that we almost never see the shark itself," said Justin Suca, an assistant professor in oceanography at UH Mānoa. "We're learning about it by studying when and where those bite marks appear."
The interdisciplinary study was led by Suca, J. Hauʻoli Lorenzo-Elarco, an assistant professor of ʻōlelo Hawaiʻi at Honolulu Community College and collaborators at the UH Hilo Ka Haka ʻUla O Keʻelikōlani College of Hawaiian Language , and Donald R. Kobayashi and Hing Ling Chan from NOAA's Pacific Island Fisheries Science Center (PIFSC).
Kobayashi, a biologist at PIFSC and UH Mānoa alumnus, has been a cookiecutter shark enthusiast for decades.
"I've been intrigued by these small sharks for over 40 years, when I first learned about them while a graduate student in oceanography at UH Mānoa and we would encounter them in net tows," Kobayashi said. "These enigmatic creatures have resisted formal study due to their habitat, behavior, and apparent rarity, so it is quite gratifying to personally contribute some solid scientific knowledge towards understanding them and their ways!"
Night patterns
Published in Marine Ecology Progress Series , the study analyzed a much larger dataset than previous research, examining bite patterns recorded across Hawaiʻi's longline fisheries over many years. The results reveal clear and persistent trends: cookiecutter shark bites occur most often at night and are closely tied to lunar cycles, with higher activity during darker, low-illumination periods.
Searching the past
Alongside the scientific analysis, the researchers reviewed Hawaiian-language sources, including historic nūpepa (Hawaiian-language newspapers), and considered knowledge shared across Polynesian cultures to better understand how the shark may have been recognized in Hawaiʻi. While no direct references were found, the team believes Hawaiian ancestors were likely familiar with the shark's distinctive bite marks.
"Our kūpuna (elders) may never have encountered the shark itself," said Lorenzo-Elarco. "But they almost certainly encountered the evidence it left behind, the distinctive bite marks on fish they brought in from the open ocean."
ʻŌlelo in science
From that understanding, the team developed a new Hawaiian name for the cookiecutter shark, nahunaiki, meaning "little bites," and created an ʻōlelo noʻeau (Hawaiian proverb) describing its bite patterns and connection to nighttime conditions. The study also includes an abstract written entirely in ʻōlelo Hawaiʻi, highlighting how Indigenous knowledge and modern science can work together to reveal patterns that might otherwise remain unseen.
These findings build on earlier UH Mānoa research that linked moonless nights to rare cookiecutter shark bites on humans , particularly swimmers in Hawaiʻi's ocean channels, suggesting darkness plays a key role across very different types of encounters.
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