Density and abundance estimation of the neotropical otter (Lontra longicuadis annectens Olfers, 1818) in the Alvarado Lagoon System, Veracruz

Background. In Mexico, the neotropical otter (Lontra longicaudis annectens, Olfers, 1818) is widely distributed, and its populations are threatened. Objectives. To estimate the density and abundance of neotropical river otters in the Alvarado Lagoon System (SLA), Veracruz. Methods. The SLA has an extension of 51,960.52 hectares and is made up of coastal lagoons, interior lagoons, and rivers. We employed the distance sampling technique with systematic transects to estimate the distribution, density, and abundance of the Neotropical otter in the SLA. Results. A total of 25 independent otter sightings were obtained; the Limón, Blanco, and Culebrilla rivers are the areas with the most significant sights. An abundance of 934 (% C.V.= 20.45) otters was estimated for the entire SLA, with a density of 0.179 organisms/km2 (% C.V.= 20.45). Conclusions. This study contributes to determining the first direct estimation of density for this species in a region of Mexico. The importance of this study is the precision with which the otter population was estimated, which allows for more robust information to make decisions and to take actions for the management and conservation of the species.