Mariana Osório Côrtes, Renato Hajenius Aché de Freitas, Penélope Bastos, Tatiana Leite
Octopus americanus Froriep, is the most significant octopus species for industrial and artisanal fishing in the Western Atlantic. Redescribed in 2020, little is known about its ecology and behaviour in the natural environment, and available data for management plans largely derive from fleet fishing landings at depths ranging from 30 to 200 m. We employed three complementary methodologies to expand knowledge on the habitat use and distribution of this species in shallow water (up to 15 m) around coastal islands in South Brazil. These methods included: (1) longline pot fishing experiments (2014–2017), (2) scuba diving collections (2021–2023), and (3) interviews with artisanal fishermen in the region (2021–2022). We sampled octopus size, abundance, diet and habitat characteristics. Octopus americanus was found throughout the year around the islands, with large individuals prevalent in winter and smaller ones in autumn. Bivalves, especially Perna perna, along with crustaceans and gastropods, were the primary items identified in the octopus’ middens, while crustaceans, fish and polychaetes were present in the stomach contents. Octopus americanus was observed across various substrate and den types associated with the rocky coast, and frequently observed at the interface between rock and sand. The species utilised the study area for breeding, feeding and growth. Our results identify critical areas to sustain O. americanus’ population, contributing to the understanding of its ecological niche and conservation. Recommendations for fisheries management are provided.