Enhancing management effectiveness of invasive lionfish using distance sampling and detection probability

Abstract

Abstract Invasive lionfish Pterois volitans and Pterois miles are one of the greatest threats to coral reef fisheries in the Caribbean. Management currently relies solely on removal, however, there is little understanding of spatial ecology of lionfish to inform management strategies and thus, increase their effectiveness. The use of detection probability and population density estimates from distance sampling as a method to: (a) estimate spatial and depth variations in detectability of lionfish to prioritize removal efforts; (b) reduce costs related to removal in the Caribbean; and (c) provide quantifiable baseline data against which management success can be measured was evaluated. Underwater visual transect surveys were conducted at varying depths at four coral reef sites in the Turks and Caicos Islands using perpendicular distance sampling. Detection functions were fitted to distance data from 299 lionfish sightings across 37 transects to explore variation in detectability among survey sites and depths. Lionfish were detected with a 15.9% (12.2–20.6%) (mean ± 95% CI) probability across all sampling. Detection probability was significantly higher in depths < 15 m, however, lionfish density and mean size increased with depth. Population density on South Caicos reefs was estimated at 1679 (1140.4–2473.1) individuals per km2. Increased detection probability in shallower depths implies caution is needed in assessing management success at depth, and that removal methods and effort should be related specifically to depth and habitat factors. Distance sampling is an effective method for accurate estimation of lionfish population density and detection probability, providing metrics by which to identify priority management areas, and track population changes along with the success of removal efforts. As a result its integration into initial planning and continued monitoring aspects of lionfish management throughout the Caribbean is recommended. Copyright © 2015 John Wiley & Sons, Ltd.