ʻAʻohe pau ka ʻike i ka hālau hoʻokahi │ One learns from many sources │ A web publication from the Office of the Chancellor, University of Hawaiʻi at Hilo
Breeann Andrade won top honors for presentation at the 2026 Hawaiʻi Conservation Conference; she studies ecological relationship between ʻōpelu fish and humpback whales.
Breeann Andrade in the field at dawn collecting ʻōpelu samples, August 2024, Hilo. (Courtesy photo from Bree Andrade)
A presentation about her investigation into the ecological relationship between mackerel scad and humpback whales in Hawaiian waters earned University of Hawaiʻi at Hilo graduate student Breeann Andrade a top award at the 2026 Hawaiʻi Conservation Conference.
Andrade received the Graduate Student Presentation Award for Best Outstanding Oral Presentation for her talk about her research, entitled, “Nutrient Pathways in Hawaiian Waters: Pilina Between Koholā and ʻŌpelu.” The conference was held on Oʻahu in July.
Andrade, who hails from Oʻahu and graduated in 2024 with a bachelor’s degree in marine science from UH Hilo, is currently a graduate student in the 2024 cohort of the university’s tropical conservation biology and environmental studies program. On the thesis track of the program, she is studying the seasonal ecological relationship between ʻōpelu (mackerel scad) and koholā (humpback whales) in Hawaiian waters.
“Specifically, I’m looking into whether ʻōpelu change what they eat, where their carbon comes from, and their trophic position during whale season, including whether or not they consume sloughed humpback whale skin,” explains Andrade, lead author of the study. “I’m using a three-pronged approach consisting of three different but complementary methods to understand this relationship: stomach content analysis, bulk stable isotopes, and compound-specific isotope analysis of amino acids of ʻōpelu during whale season and non-whale season across three sampling locations: Hilo, Kona, Maui Nui.”
Co-authored by faculty advisors, the research summary states “these patterns showcase localized, seasonal changes in ʻōpelu feeding ecology consistent with intermittent consumption or indirect incorporation of whale-derived nutrients, and highlighting how recovery of native megafauna may contribute to the regeneration, stability, and function of marine food webs and fisheries in Hawaiʻi for future generations.”
Bree Andrade measures the length of ʻōpelu using a bump board. Click/tap images for full size.
Bree Andrade in the lab counts and identifies the plankton found within the stomach contents of ʻōpelu.
Bree Andrade takes a selfie in the lab while conducting stomach content analysis of ʻōpelu. (Courtesy photos from Breeann Andrade)
A meaningful award: “Ultimately, I want the information to make its way back to the people who can use it, and not just stay in academia, because I do believe that caring and taking care of Hawaiʻi is a kākou thing.”
Andrade says her research is an important way for her to “give back to the community” that raised her.
“I was born and raised on the island of Oʻahu, and with that being said, I have always wanted to give back to the place and community that raised me, and research became my way to do that,” she says. “I’m not completely sure what the recognition (award) itself means to me, but I know it means a lot that people were able to positively connect with the research/work.
“I feel honored that this project allows me to uplift ʻike kūpuna/kuʻuna (ancestral knowledge/ tradition) and the ancestors that were researchers long before me on a larger scale,” she adds. “This recognition feels like a success in the way that I was able to shine a light on the knowledge, observations, and relationships that made this work possible. Because, ultimately, I want the information to make its way back to the people who can use it, and not just stay in academia, because I do believe that caring and taking care of Hawaiʻi is a kākou (we) thing.”
Summary of the study
Nutrient Pathways in Hawaiian Waters: Pilina Between Koholā and ʻŌpelu
Bree Andrade gives her presentation at the 2026 Hawaiʻi Conservation Conference held on Oʻahu in July 2026. Click or tap for full size. (Courtesy image from Bree Andrade)
Koholā (humpback whales, Megaptera novaeangliae) are ecosystem engineers that redistribute nutrients and organic matter and support ecosystem function. In Hawaiian waters, Koholā contribute a minimum of 29 MT of biomass annually, which may act as a localized allochthonous subsidy supporting marine ecosystem regeneration. While whale falls and whale pumps are well documented, the ecological role of sloughed whale skin remains poorly understood. Photographic and video evidence show ʻōpelu (mackerel scad, Decapterus macarellus), a native epipelagic forage fish, feeding on or near Koholā in the Hawaiian Islands Humpback Whale National Marine Sanctuary (Maui, USA), suggesting a potential seasonal trophic interaction. To investigate this, ʻōpelu were collected in whale (November-April) and non-whale (May-October) seasons from windward and leeward Hawaiʻi Island and leeward Maui. Stomach contents were visually assessed, and muscle and gonadal tissues were analyzed for bulk d13C and d15N to evaluate seasonal and spatial trophic patterns. Stomach contents showed reduced zooplankton reliance during whale season. Isotopes showed spatial structuring and tissue-specific responses. Muscle tissue overlapped between seasons, whereas ovarian tissue was more seasonally variable, with d13C overlapping with Koholā epidermal tissue but d15N remaining distinct. Seasonal isotope responses were strongest in Maui, where whale densities are relatively higher. Collectively, these patterns showcase localized, seasonal changes in ʻōpelu feeding ecology consistent with intermittent consumption or indirect incorporation of whale-derived nutrients, and highlighting how recovery of native megafauna may contribute to the regeneration, stability, and function of marine food webs and fisheries in Hawaiʻi for future generations.
UH Hilo at the 2026 Hawaiʻi Conservation Conference
Several other students from the tropical conservation biology and environmental science graduate program also presented their work at the conference.
“Great showing all around,” says Ryan Perroy, professor of geography and environmental science and past director of the graduate program. “We had quite a strong presence and it was wonderful to see so many current and past students there interacting together and sharing their important conservation work.”
Story by Susan Enright, public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.
