A recent countrywide status survey of the critically endangered central American river turtle (Dermatemys mawii) in Belize
- TR Rainwater, T Pop, O Cal, A Garel, SG Platt, R Hudson
- Chel Conserv Biol
Monitoring rare aquatic reptiles in turbid rivers and lagoons is complicated by low detection rates due to low visibility. We tested the use of side-scan sonar as a simple, rapid method for detecting turtles and identifying areas of high activity that could then be targeted with capture methods. We compared detection rates of turtles (Dermatemys mawii and Trachemys venusta venusta) in the New River Lagoon, Belize, using sonar, visual surveys, trammel nets, and baited traps. Sonar surveys detected 0.75 turtles/h (daytime) and 4 turtles/h (nocturnal surveys). In comparison, visual surveys detected 0 turtles/h; hoop traps detected 0.003 turtles/h; and trammel netting detected 1.75 turtles/h. Sonar surveys also detected Crocodylus moreletii (0.28 crocodiles/h). Sonar surveys do not directly facilitate capture and identification, and the efficacy of this method varies with the depth and substrate of the survey area. Sonar surveys are a useful preliminary detection tool for large aquatic reptiles in turbid waterways with soft substrate, allowing rapid, preliminary presence–absence surveys and identification of activity hotspots.