Developing a population assessment for Caribbean spiny lobster Panulirus argus in the United States Virgin Islands: lessons learned

Abstract

The Caribbean spiny lobster (Panulirus argus) is one of the most important fisheries in the US Virgin Islands. Low densities and life-history characteristics of lobsters have made reliable surveys in the region notoriously difficult, contributing to sparse and inconsistent fisheries-independent datasets to inform management decisions. Many existing and historical surveys are limited in their temporal and spatial coverage. In 2019, the National Park Service initiated a long-term monitoring effort of spiny lobsters in Buck Island Reef National Monument and Salt River Bay National Historical Park and Ecological Preserve, St. Croix, US Virgin Islands, and Virgin Islands National Park, St. John, US Virgin Islands. Initial surveys show both density (3.06–7.07 lobsters ha−1) and occupancy (0.11–0.12 sites with lobster) are low and not significantly different between the three parks. While survey efforts are currently focused on national parks, the 50 × 50 m gridded sample frame and stratification scheme are adaptable to the wider US Caribbean region, modelled after the multi-agency design to monitor reef fish with the National Coral Reef Monitoring Program. With the same survey footprint as reef fish surveys, the two methods could conceivably be co-located in the future, improving cost-efficiency and overall data quality. If expanded, this methodology could provide regional fishery managers with much needed density indices, though future surveys would benefit from a greater sample size or by supplementing with other methods that increase the number of observed lobsters to allow for robust size-frequency analyses.