Habitat preferences and migratory patterns of the blue shark (Prionace glauca) in the Northern Atlantic Ocean

The blue shark (Prionace glauca) is a highly migratory, pelagic, circumglobally distributed species whose fins constitute by far the largest proportion of fins traded in the in the world market.  Despite its highly exploited status, relatively little is known about the complex and likely sexually-biased, long-term or short-term movement patterns of this species.  Conventional tagging and observational data indicate that blue sharks are common off the coast of the northeastern US during the summer months May-September.  To investigate the short-term environmental preferences of blue sharks on the continental shelf off the northeastern US during summer months, PTT-100 archival, High Rate archival and X-tags (Microwave Telemetry) were fitted to seven individuals in June 2007.  The tags recorded depth, temperature, and light data at either 3 or 15 minute intervals.  A total of 104 days of data was archived.  Of the seven sharks tagged (males=5, females=2).  Sharks spent a large proportion (79.5%) of time within 10 m of the surface with infrequent dives to greater depths; average depth for females was 3.2 m and for males, 6.8 m.  One shark, which retained its tag for 6 weeks, exhibited more frequent diving behavior and traveled a distance of 341.2 km between tag deployment and tag release locations, however it predominantly remained on the continental shelf.  

click on the tag for a short video on the satellite tag