Observations of cetaceans in the waters of the Surtsey Nature Reserve between 2008 and 2021

The island of Surtsey originated from an underwater eruption in 1963 and has since been studied extensively, illustrating the colonization and succession by numerous species in both the terrestrial and marine habitats. However, there is little information on the cetaceans occurring near the island. Here we show that killer whales, pilot whales and minke whales are observed within the Surtsey Nature Reserve in June-August, although survey effort within this area has been lower than in other parts of the Vestmannaeyjar archipelago. Thus, we expect the list of species will increase with higher effort in the future. Killer whales were the species observed most commonly and were seen during the summer months, most often on the east and north coasts. Both observational and animal-attached tag data suggest killer whales were feeding within the reserve, and the only prey identified was herring. However, seasonal survey effort limits a comprehensive understanding of the prey killer whales may target within this area and particularly whether killer whales may target the seal colonies established here during autumn and winter. In the future, increased effort in summer and at other times of the year, would help fill in these gaps in our knowledge of the importance of the Surtsey nature reserve for cetaceans.