We are monitoring the movement and residence time of reef fish among habitats in two underwater parks under different management strategies in the U.S. Virgin Islands. Our objectives are to document the condition of the fish and their habitat preferences and establish how the habitats are linked through fish movements. Results of this study will help park officials understand the influence of different management strategies on the fish and guide the coordination of management strategies.
Why We Care
Fish in the U.S. Virgin Islands play an important economic and cultural role. Understanding the habitat preferences and the movement of fish is essential to responsibly manage ecosystems and sustain healthy populations of fish. The need is especially critical in places such as underwater preserves and parks, where the movement of fish can affect park size and boundary decisions and management approaches.
What We’re Doing
To date, we deployed an array of 36 underwater hydroacoustic receivers in strategic locations across the bays and coral reefs around the southern shores of St. John. Then we surgically implanted transmitters into 150 fish composed of 18 species and 10 families and recorded their movements. We used the data to analyze the sizes of species’ home range, migratory patterns, and habitat preferences. In Phase 1 of this project we focused on movements of fish along shore. Phase 2, which began in 2012, focuses on the fish movement offshore.
What We’re Finding
Results from this study indicate that lane snappers and blue striped grunts, for example, move from reef habitats during daytime hours to offshore seagrass beds at night. The array of acoustic receivers was located in both near-shore and cross-shelf locations, providing information on fine- to broad-scale fish movement patterns across habitat types and among management units. Based on fish movement results, we are able to examine the strength of ecological connectivity between management areas and habitats.
Phase I of this project was completed in 2008. We began additional studies in 2012 that focus on inshore/offshore movements of fish around St. John. Beginning in 2014, we will move the investigation to the nearby island of St. Croix. This Island has a different arrangement of habitats and management landscape and can be used as a comparison to findings from St. John.