Data from: Seasonality and relative abundance within an elasmobranch assemblage near a major biogeographic divide

Nearshore waters are utilized by elasmobranchs in various ways, including
foraging, reproduction, and migration. Multiple elasmobranch species have
been previously documented in the nearshore waters of North Carolina, USA,
which has a biogeographic break at Cape Hatteras on the Atlantic coast.
However, comprehensive understanding of the elasmobranch community in this
region is still lacking. Monthly year-round trawling conducted along two
ocean transects (near Cape Lookout and Masonboro Inlet in 5 to 18 m depth)
in Onslow Bay, North Carolina provided the opportunity to examine the
dynamics and seasonal patterns of this community using a multivariate
approach, including permutational multivariate analysis of variance and
nonparametric BIO-ENV analysis. From November 2004 to April 2008, 21,149
elasmobranchs comprised of 20 species were caught, dominated by spiny
dogfish (Squalus acanthias) and clearnose skate (Rostroraja eglanteria).
All species exhibited seasonal variation in abundance, but several key
species contributed the most to seasonal differences in species
composition within each transect. Spiny dogfish was most abundant in the
winter at both locations, comprised mainly of mature females. Although
clearnose skate was caught in all seasons, the species was most abundant
during the spring and fall. Atlantic sharpnose (Rhizoprionodon
terraenovae) was one of the most abundant species in the summer, and two
distinct size cohorts were documented. Temperature appeared to be the main
abiotic factor driving the community assemblage. The extensive year-round
sampling provided the ability to better understand the dramatic seasonal
variation in species composition and 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 the biogeographic break at
Cape Hatteras.