Smooth hammerhead sharks (Sphyrna zygaena) observed off the Portuguese southern coast

Seasonal Movements and Habitat Use of Juvenile Smooth Hammerhead Sharks in the Western North Atlantic Ocean and Significance for Management

“…The sharks we tracked in the western North Atlantic Ocean displayed consistent seasonal movements between core areas of activity off Long Island, New York in summer and off Cape Hatteras, North Carolina in winter. Although seasonal movements of this species have been hypothesized previously based on surface sightings (Couto et al, 2018) and fisheries catch per unit effort data (Santos and Coelho, 2019) in the eastern North Atlantic, the telemetry results here provide a direct, fishery independent demonstration of this behavior by smooth hammerheads. Based on environmental characteristics of the core areas, sea surface temperature and productivity appear to be important drivers of their seasonal movement patterns, as has been demonstrated in other highly migratory marine megafauna (Weng et al, 2008;Block et al, 2011;Curtis et al, 2014;Kajiura and Tellman, 2016;Vaudo et al, 2017).…”

“…These studies illustrate the possibility that movements and behavior of smooth hammerheads may be influenced by thermal heterogeneity of their environment. Very little information on relationships between other environmental variables (primary productivity, oceanic fronts, water depth) and movements of smooth hammerheads exists (Couto et al, 2018), although these variables have been shown to greatly influence movement and habitat selection of highly mobile sharks (Block et al, 2011;Queiroz et al, 2016;Vaudo et al, 2017). Understanding interactions between patterns of habitat use and environmental variables would contribute toward construction of habitat models and an improved ability to predict the distribution of smooth hammerheads under climate change scenarios, as well as reveal potential interactions with human activities throughout their range.…”