Advancing Understanding of Goliath Grouper Behavioral Ecology

The Atlantic goliath grouper (Epinephelus itajara) is a large (max 360 kg, 250 cm) tropical and subtropical marine fish found on rocky reefs and wrecks at depths of up to 100 m. Their predictable spawning aggregations and life history traits have made them highly susceptible to overfishing which led to their status as “critically endangered” on the International Union for Conservation of Nature (IUCN) Red List. After decades of conservation efforts and signs of recovery, the IUCN status was changed to “vulnerable” in 2018. Despite this, there are few behavioral studies of free-ranging goliath grouper. Goliath grouper produce low frequency, high intensity sounds (i.e., “booms”) associated with courtship/spawning and antagonistic behavior, which may be distinguished according to boom duration and frequency. Here we present a custom-built, multi-sensor tag developed with the aim of elucidating the behavioral ecology of wild goliath grouper. We incorporated a hydrophone for monitoring acoustic responses, accelerometer/magnetometer/gyroscope for measuring kinematic movement, a SPOT tag and VHF transmitter for facilitating tag retrieval, and a video camera for ground-truthing behavioral data obtained from animals at liberty. We also present preliminary findings from our experiments.