UH Graduate Researches Reef Fish Sustainability

Jennifer Wong-Ala works on the computer model. Photo courtesy of University of Hawai‘i at Mānoa.

Adult reef fish, such as yellow tang, strategically release eggs in places where they will be swept into the open ocean and survive their larval stage. Once they are mature enough, the fish return to the reef in a process termed “recruitment.” Recruitment can be influenced by factors like ocean currents, as well as biological strategies like when and where the fish are born, and how long they remain in the larval stage.

Wong-Ala, who graduated in the spring of 2017 from UHMʻs Global Environmental Science (GES) degree program, worked with her mentor, oceanography assistant professor Anna Neuheimer, to develop a computer model to gather data on reef fish populations. These included date of birth, location of birth, movement of larvae, duration of the larval stage, development settlement and death of larval reef fish off the shores of Hawai‘i Island.

Their research found that recruitment changed depending on the fishʻs birthdate due to influences like currents, eddies and moon phases, which alter tides. Birth location also made a difference. Fish born in shallow waters and sheltered bays showed higher rates of return to their home reefs compared with those born in unsheltered locations.

“This study provides a baseline understanding of how biophysical factors interact to impact recruitment in western Hawai‘i Island,” said Wong-Ala, who was born and raised in Waimānalo on Oʻahu.

The findings shed light on the variations in recruitment between different species from year to year, and may predict possible changes in the future. Understanding the number of fish who return to their home reef is an important aspect of maintaining sustainable populations.

“I chose GES because it is an interdisciplinary major that allows us to learn about the changes in the environment, gain valuable computer skills, and focus on what we are truly interested [in],” said Wong-Ala. “My favorite aspect of my thesis experience is the relationship that developed with my mentor. I have worked in her lab for three years and it has been an experience that has taught me so much. I hope to be a mentor like her in the future.”

Having recently graduated on May 13, Wong-Ala is preparing to enter a graduate program at Oregon State University in Ocean, Earth and Atmospheric Sciences.