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Presentation TitlePOSTER: Seasonality and relative abundance of elasmobranchs near the northern boundary of a biogeographic break
Presenting Author NameGrace Roskar
Presenting Author AffiliationInstitute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell St., Morehead City, NC 28557, USA
Presenting Author EmailEmail hidden; Javascript is required.
Presentation Number2
Unit MeetingTidewater Chapter
General Topicelasmobranch ecology
Type of PresentationPoster

Nearshore waters (within 10 km of shore) are utilized by elasmobranchs in various ways, including foraging, reproduction, and migration. Several elasmobranch species have been previously documented in the nearshore waters of Onslow Bay, North Carolina but comprehensive understanding of the elasmobranch community in this region is still lacking. Monthly year-round trawling in Onslow Bay provided the opportunity to examine the dynamics and seasonal patterns of this community using a multivariate approach. Trawling was conducted along two transects (Cape Lookout and Masonboro Inlet) from November 2004 to April 2008. Overall, 21,149 elasmobranchs comprised of 20 species were caught. Spiny dogfish Squalus acanthias and clearnose skate Raja eglanteria were the most abundant species overall. Within each transect, species composition differed among seasons and there were several key species contributing to the seasonal differences. For example, spiny dogfish were only abundant in winter and Atlantic sharpnose were only abundant in summer. Moreover, temperature was the main abiotic factor driving the community assemblage. Overall, the extensive year-round sampling provided the ability to better understand the dramatic seasonal variation in species composition, and also highlights the relative abundance of several understudied elasmobranch species that may be of significant ecological importance. Our results underscore the importance of inner continental shelf waters as important elasmobranch habitat and provide baseline data to examine for future shifts in timing and community structure at the northern portion of a biogeographic break.