Feeding habits of the Guiana dolphin, Sotalia guianensis, (Van Bénéden, 1864) (Cetacea: Delphinidae) in Sepetiba and Ilha Grande bays, southeastern Brazil

The analysis of gastrointestinal contents of dead animals is the primary and most traditional technique used to investigate cetacean feeding habits. The Guiana dolphin (Sotalia guianensis) is among the most common cetacean species on the Brazilian coast. Sepetiba and Ilha Grande bays currently house this species’ highest population estimates. The present study aims to characterize the feeding habits of the Guiana dolphin between 2007 and 2021 by analyzing the stomach contents of individuals found dead in Sepetiba and Ilha Grande bays. Based on this analysis, we compared feeding habits according to gender, sexual maturity, seasonality, and location. We also investigated the feeding habits of this species during the morbillivirus event. The diet of the Guiana dolphins of Sepetiba and Ilha Grande bays was predominantly composed of teleost fish, with cephalopods being the second most consumed prey. The prey family most present in the diet of the Guiana dolphin in Sepetiba and Ilha Grande bays was the teleost fish Sciaenidae. Although these populations live in very close environments, they show distinct feeding habits. The conservation of these ecosystems is crucial for preserving Guiana dolphins and other species that use Sepetiba and Ilha Grande bays to live, reproduce, and feed.