The Role of Wind on the Simulated Dispersal and Recruitment of a Commercially Important Hawaiʻi Bottomfish

Abstract

Variability in larval transport has long been hypothesized to drive recruitment fluctuations in fishes, yet evidence for these hypotheses is often lacking. Further, the origins of many of these hypotheses come from temperate to subpolar regions, leaving such questions largely underexplored for other regions, especially the tropics. To assess drivers of larval transport in a tropical archipelago, we simulated the dispersal of a culturally and commercially important bottomfish, uku (Aprion virescens), from Penguin Bank, its most prominent spawning location in the main Hawaiian islands. We used Lagrangian particle tracking models forced by a regional ocean model to assess the degree of interisland potential connectivity from this spawning location and the drivers of interannual variability in this potential connectivity across 13 years from 2008 to 2020. Simulated uku larvae released from Penguin Bank primarily reached Maui Nui and Oʻahu, the nearest potential settlement areas, with lower potential connectivity to more distant regions. Interannual variability in overall number of connections was pronounced and linked both to local wind speed and direction, with increased particle loss occurring during higher overall wind speeds and more northerly winds. Recruitment deviations from the stock assessment of uku showed a similar pattern, with recruitment estimates significantly decreasing during years of strong northerly winds. Our results provide evidence, derived from a simulation model integrating ecological and physical components, of larval dispersal patterns contributing to the recruitment of a socioeconomically important species and sensitivity of these patterns to local wind forcing. Understanding how these wind patterns will change in a warming climate may be essential to understanding patterns in uku recruitment in coming years.