Jennifer Wong-Ala, a 2017 spring graduate from the University of Hawaiʻi at Mānoa’s Global Environmental Science (GES) degree program, conducted original research to determine how biological and physical factors affect the number of fish surviving to sustain populations of reef fish off West Hawaiʻi Island.
Adult reef fish, like yellow tang, release eggs strategically—in places where the eggs can be swept into the open ocean to live out their free-floating larval stage and develop until they are ready to come back to the reef. This process of successfully returning home, termed recruitment, can be influenced by many physical factors including ocean currents, as well as biological strategies such as when and where fish larvae are born and how long the fish remain in the free-floating larval stage.
To explore the influence of these factors, Wong-Ala and her mentor, oceanography assistant professor Anna Neuheimer, developed a computer model which accounted for date of birth, location of birth, movement of larvae, duration of the free-floating larval stage, development, settlement and death of larval reef fish off of Hawaiʻi Island.
Their study found that recruitment changed depending on the fish’s birthdate due to influences of the currents, eddies and moon phase (i.e. tides). Additionally, location of birth mattered, with individuals born in shallow and sheltered bays having higher rates of recruitment compared to individuals born in unsheltered locations under certain conditions.