A Diet Analysis of Wahoo (Acanthocybium solandri) from the Pelagic and Hawaiian Nearshore Ecosystems Using Visual and Metabarcoding Techniques

Diet studies are an informative way to gather basic information on the ecology of a given organism. Wahoo (Acanthocybium solandri) is a globally popular commercial, sport, and recreational fish species but currently, detailed information is lacking on their diet composition in the Pacific Ocean. We collected 450 stomachs from the Hawaiian offshore longline and nearshore troll fisheries from June to December 2014. To increase the taxonomic resolution of prey identifications, the CO1 region of the mtDNA genome was sequenced for individual prey items that could not be identified to species level visually. Clear spatial and temporal shifts in prey composition were observed in both fisheries. For nearshore-caught wahoo, juvenile pre-settlement reef species from various families dominated the prey composition during summer, followed by mackerel scad in the fall. Gempylidae, Echeneidae, and Molidae were common and temporally consistent prey families consumed by wahoo caught in the offshore fishery. Reef fishes present in stomachs from the offshore fishery were from families with extended juvenile pelagic stages in Order Tetraodontiformes. The diet composition of wahoo is indicative of an opportunistic feeder and thus reveals dominant geographic and seasonal abundances of certain prey taxa from various ecosystems in the marine environment.