Long-term residency and movements of yellowmouth barracuda (Sphyraena viridensis) at a shallow seamount

Abstract

The yellowmouth barracuda Sphyraena viridensis, a highly mobile predator, is considered a migratory seasonal visitor to the Azores Islands by local fishers. This perception is challenged here through a combined analysis of multi-annual commercial landings, underwater visual census and telemetry data from acoustically tagged fish to investigate the long-term movement patterns and residency (up to 4 years) in a seamount marine reserve. Although the landing patterns suggested a strong seasonal variation in abundance, the visual census and the telemetry experiment results were consistent with year-round residency in the Azores. Barracudas occurred consistently in underwater census throughout the year, and most tagged fish were almost continuously detected at the seamounts for up to four consecutive years. Detection probability did, however, decrease over time and showed seasonal variability as tagged fish were less mobile with longer absences during summer and fall. Given the intrinsic vulnerability of fish aggregations to exploitation, our results highlight the need to protect shallow seamount habitats and preserve sexually mature fish aggregations and their reproductive potential, contributing to the sustainable management and conservation of these vulnerable ecosystems.