ARTICLE Diet and foraging opportunism of the Guiana Dolphin (Sotalia guianensis) in the Abrolhos Bank, Brazil Vitor Leonardo A. Rodrigues 1 | Leonardo L. Wedekin 2 | Milton César C. Marcondes 3 | Lupércio Barbosa 4 | Ana Paula C. Farro 1,5 1 Programa de Pós-graduaç~ ao em Oceanografia Ambiental, Universidade Federal do Espírito Santo (UFES), Vitória, Espírito Santo, Brazil 2 LAGE do Instituto de Biociências, Universidade de S~ ao Paulo, S~ ao Paulo, S~ ao Paulo, Brazil 3 Instituto Baleia Jubarte, Caravelas, Bahia, Brazil 4 Instituto ORCA, Vila Velha, Espírito Santo, Brazil 5 Laboratório de Genética e Conservaç~ ao Animal (LGCA), Centro Universitário Norte do Espírito Santo (CEUNES), UFES, S~ ao Mateus, Espírito Santo, Brazil Correspondence Vitor Leonardo A. Rodrigues, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo (UFES), Vitória, Espírito Santo, Brazil. Email: vitor_leo@hotmail.com Abstract Diet analysis allows exploring how coastal dolphins interact with the environment and their role in the marine food webs. We studied the diet and feeding ecology of the Guiana dol- phin, Sotalia guianensis, through analysis of stomach content from 42 animals stranded on the eastern coast of Brazil. A total of 1,336 semidigested prey items (fish, otoliths, cepha- lopod beaks, and crustaceans) were identified. Teleost fish comprised the most frequent food item (92% of the total), followed by cephalopods, and crustaceans. Prey belonged to 34 taxa and richness in individual stomachs varied from 1 to 15 prey taxa. Prey were generally small, but showed a signifi- cant trend to increase in size with dolphin length. The main prey of Guiana dolphins were demersal, estuarine, and sound-making fish such as catfish and sciaenids. No sex- related differences in diet were found. Diet composition var- ied seasonally and occurrence of prey items was coherent with breeding or high abundance periods of some fish spe- cies and squids. Our study shows the importance of demersal prey from estuarine and soft-sediment habitats to Guiana dolphin in the Abrolhos Bank and reveals that feeding habits are generalist and opportunistic, with diet reflecting the sea- sonal abundance and availability of prey. Received: 24 June 2018 Revised: 10 September 2019 Accepted: 1 October 2019 DOI: 10.1111/mms.12656 Mar Mam Sci. 2019;1–15. wileyonlinelibrary.com/journal/mms © 2019 Society for Marine Mammalogy 1