Residency, space use and movement patterns of juvenile sandbar sharks (Carcharhinus plumbeus) within a Virginia summer nursery area
C. L. Conrath A B C and J. A. Musick AA Virginia Institute of Marine Science, College of William and Mary, PO Box 1346, Gloucester Point, VA 23062, USA.
B Present address: NOAA, NMFS, Alaska Fisheries Science Center, Kodiak Laboratory, Kodiak Fisheries Research Center, 301 Research Court, Kodiak, AK 99615, USA.
C Corresponding author. Email: Christina.Conrath@noaa.gov
Marine and Freshwater Research 61(2) 223-235 https://doi.org/10.1071/MF09078
Submitted: 4 April 2009 Accepted: 6 August 2009 Published: 25 February 2010
Abstract
Neonates and juveniles of many large coastal shark species occupy shallow inshore nursery areas during portions of the year. The identification of how these areas are used by large coastal shark populations is an important consideration in conservation and management efforts. An array of passive acoustic receivers was utilised to track the movements of 64 neonate and juvenile sandbar sharks within the Eastern Shore of Virginia summer nursery during the summers of 2003–2005. Residency patterns were variable during each year of the study, with younger sandbar sharks spending more time within the array area than older sharks. The number of detections was positively related to the distance of the receiver inshore from the inlet, indicating that young sandbar sharks preferentially utilise protected, shallow near-shore waters. Neonate and juvenile sandbar sharks tended to be detected more frequently within all areas of the inlet at slack tides, during the night and during early dawn hours. Periodogram analyses indicated that juvenile sharks tend to move in the direction of tidal currents. The present study documents large- and small-scale movement patterns of juvenile sandbar sharks and emphasises the importance of nursery-area habitats for this species.
Additional keywords: acoustic monitoring, elasmobranch, essential fish habitat, refuge.
Acknowledgements
We thank P. G. Ross, S. Fate, A. Birch, E. Smith, G. Arnold and R. Bonniwell for excellent field and logistical support. Thanks go to the Virginia Institute of Marine Science shark project for assistance rendered, particularly J. Ellis, J. Smith, L. Pace and J. Romine. We also thank C. Simpfendorfer and M. Heupel for assistance with data analyses. We thank three anonymous referees for comments that greatly improved this manuscript. Funding for this project was provided by Saltonstall–Kennedy Grant NA17FD2365 and by the National Shark Research Consortium. Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA.
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