Assessing Guiana dolphin abundance and density in the Southwestern Atlantic: insights from conservation areas

Accurate demographic data play a critical role in implementing conservation strategies and identifying key areas for species preservation. The population abundance and density of Sotalia guianensis were estimated in the estuarine-lagoon complex of Cananeia, Brazil, using distance sampling. The survey covered 1339.91 km with 83 h 05 min in effort. A half-normal model with cosine adjustments was evaluated as the best fit to estimate an abundance of 193 individuals (95% CI 158-237) and a density of 2.55 ind km(-2). The majority of sightings occurred in the Baia de Trapande (48.72%), followed by the Mar de Cananeia (32.72%) and Mar de Cubatao (18.56%), the three areas surrounding the Ilha de Cananeia. The study confirmed the heterogeneous distribution of the estuary and found that the Mar de Cananeia and the Baia de Trapande were more densely populated, with 2.76 ind km(-2) (95% CI 1.93-3.96) and 2.76 ind km(-2) (95% CI 2.07-3.66), respectively, while the Mar de Cubatao was less densely populated, with 1.59 ind km(-2) (95% CI 1.04-2.44). The findings support previous research indicating a stable population over the last few decades. The Cananeia estuary is an ecologically diverse region located between protected areas under different categories of environmental protection and harbours a significant population of S. guianensis, providing essential resources for feeding and breeding. Protected areas have proven to be effective tools for preserving both marine and terrestrial environments. Despite the close proximity to humans and constant threats, the study underscores the importance of the area for the conservation of the species.

Automated summary

Accurate demographic data are crucial for implementing conservation strategies and identifying key areas for species preservation. This study estimated the population abundance and density of Sotalia guianensis in the Cananeia estuarine-lagoon complex in Brazil using distance sampling. The results showed heterogeneous distribution of the species in different areas, emphasizing the importance of the region for conservation.