Insights into ‘opihi and ‘ōpelu fisheries using oceanographic modeling, experiments, and sociological investigations

Abstract

Distribution and abundance of marine resources are affected by various abiotic and biotic factors ranging from temperature, dissolved oxygen, presence or absence of competitors, and food availability. In this dissertation, I examined the role of several environmental variables in shaping distribution and abundance of two important living resources in Hawai‘i, ‘Opihi Makaiauli (Limpet, Cellana exarata) and ‘Ōpelu (Mackerel Scad, Decapterus macarellus), through larval development experiments and larval transport models (‘Opihi), and fisher interviews and species distribution models (‘Ōpelu). ‘Opihi Makaiauli is one of three endemic limpet species in Hawai‘i, collectively referred to as ‘Opihi. For ‘Opihi Makaiauli, larval development and time to metamorphosis have been reported in the literature only once and how water temperature affects the ability of embryos and larvae to develop and survive has not yet been determined for any of the three species, to our knowledge. The two studies that have modeled larval dispersal of ‘Opihi Makaiauli included several islands in the Hawaiian chain, but connectivity has not been modeled across the entire archipelago. In my first data chapter (Chapter 2), I evaluated the effects of temperature on the survival of embryos and larvae of ‘Opihi Makaiauli and described the timing of their development from fertilization to metamorphic competence. I applied the result from the larval rearing experiment to my second data chapter (Chapter 3), a larval transport model of ‘Opihi Makaiauli. For my third data chapter (Chapter 4), I evaluated the environmental factors influencing ‘Ōpelu aggregation behavior and catchability by combining fisher knowledge and fishery-dependent data to create a model of ‘Ōpelu catch.