Abstract

Many large coral reef fish participate in transient fish spawning aggregations (tFSAs), events at certain times of year during which fish migrate tens of hundreds of kilometers to spawn in large groups at specific locations. One such species of economic and ecological importance in the US Virgin Islands is the mutton snapper (Lutjanis analis). They are known to use a site called Tampo, south of the island of St. John, a site on the southwest end of St. Croix, and are suspected to use a site on the Grammanik Bank, south of St. Thomas. The search for the locations of these aggregations and their source populations is an active area of research. To track individuals to and from aggregation sites, this study utilized passive acoustic telemetry, an effective method for quantifying spatiotemporal movements of many fish for long, continuous periods of time. Arrays were placed at the three spawning sites across the US Virgin Islands, as well as at Brewers Bay, St. Thomas, and Buck Island, St. Croix. Eight individuals were tagged in Brewers Bay, with all but one showing high residence time of >90% by hour for most of the year. Two swam from home sites in Brewers Bay, bypassed the closer aggregation at the Grammanik Bank, and swam to the spawning site at Tampo, while one tagged at the spawning site in St. Croix swam to its home site at Buck Island. This study compares movement patterns of mutton snapper at their home ranges to those at spawning sites. Species like mutton snapper are vulnerable to fishing during reproductive periods, due to a high concentration of large fish at predictable times and places. Knowledge of fish space use is essential to the implementation of effective management strategies that can benefit both the local economy and the environment, ensuring sustainability and ecosystem health for the long term.

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