The blue shark (Prionace glauca) is among the most abundant and widely distributed of all oceanic elasmobranchs. Millions of blue sharks are caught annually worldwide in pelagic long line fisheries, and it accounts for the largest component of auctioned fin weight in the international shark fin trade. There is growing concern about the depletion of its populations worldwide and impacts of such large scale removal of an apex predator on oceanic ecosystem stability. The fragmentary nature of life history information available for blue sharks, including on its detailed movement and migratory behavior, continues to limit management efforts that require such data for stock assessment and sustainable catch modeling. To assist in obtaining a better understanding of blue shark movement behavior in the western north Atlantic, I used satellite telemetry to investigate the detailed habitat utilization and movements of sharks during the summer months when the sharks form aggregations on the continental shelf off the Northeast United States, and during their fall , pelagic migrations. Thirty-one (26 male, 5 female) blue sharks were tagged with pop-up archival satellite transmitters. The transmitters reported data from a total of 1,656 combined days, yielding 74,163 depth recordings and 74,125 temperature recordings. Tracked sharks exhibited two distinct movement patterns: During the summer months, the sharks remained within a restricted geographical area south of Nantucket Island and spent nearly 80% of their time in the uppermost part of the water column in 4,000 km). There was some indication that the different demographic groups (mature males, immature males, and immature females) may display different movement behavior, especially during their pelagic migrations. This study provides the first detailed information on habitat utilization and movement patterns of blue sharks in the Western North Atlantic, and points to the need for further investigation of movement behavior by different demographic segments of the population.
| Date of Award | Mar 1 2010 |
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| Original language | English |
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| Supervisor | Mahmood S. Shivji (Supervisor), Bradley M. Wetherbee (Advisor) & Richard E. Spieler (Advisor) |
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