Opportunistic sighting of a silky shark (<i>Carcharhinus falciformis</i>) aggregation in the subtropical southwest Atlantic

Silky shark (Carcharhinus falciformis) populations in the South Atlantic Ocean are listed as vulnerable under the IUCN. In fact, this species is classified as critically endangered in Brazil under the Ministry of the Environment. The present study reports the first opportunistic sighting of an aggregation of 250-300 silky sharks in the Alcatrazes Archipelago Wildlife Refuge. Aggregation sites are important in the life cycle of silky sharks, and identifying these sites is essential for conservation efforts.