Document: Article

Abstract: Studying the abundance, distribution, and habitat use of dolphins can provide essential information for preserving marine biodiversity, managing coastal ecosystems, and enhancing our understanding of aquatic life. Herein, we investigated the abundance, distribution, and habitat use of two dolphin populations—Guiana dolphins (Sotalia guianensis) and common bottlenose dolphins (Tursiops truncatus)—in the Gulf of Urabá, Colombian Caribbean. Between 2017 and 2020, 34 non-systematic surveys were conducted across the studied region, amounting to an effort of 176.69 hours and covering 3,658.33 km, with a dolphin encounter probability rate of 8.65%. The Guiana dolphin population was estimated at 63 (95% CI = 53 to 76) individuals, whereas the common bottlenose dolphin population was estimated at 50 (95% CI = 43 to 58) individuals. The dolphins were mainly found in the central region of the Gulf, particularly around the Atrato River mouth and the east side of the estuary. Both species showed a preference for coastal areas with maximum depths of 20 m, and the Guiana dolphins showed a permanent presence in the Gulf of Urabá region. These findings indicate that the Gulf of Urabá acts as a crucial habitat and feeding ground for both Guiana and common bottlenose dolphins. Therefore, systematic monitoring programmes aiming to protect dolphin populations and their ecosystems from threats posed by coastal development, which currently endanger both species in the area, should be implemented.

Key Words: cetaceans, coastal populations, conservation, maximum-entropy analysis, population parameters, Colombia

DOI: https://doi.org/10.1578/AM.50.5.2024.383

Page Numbers: 383-401