Utility of mesohabitat features for determining habitat associations of subadult sharks in Georgia’s estuaries

Environmental Biology of Fishes
National Marine Fisheries Service; National Marine Fisheries Service's Highly Migratory Species Division; US Geological Survey; U.S. Fish and Wildlife Service, GA Department of Natural Resources; University of Georgia; Wildlife Management Institute
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Abstract

We examined the affects of selected water quality variables on the presence of subadult sharks in six of nine Georgia estuaries. During 231 longline sets, we captured 415 individuals representing nine species. Atlantic sharpnose shark (Rhizoprionodon terranovae), bonnethead (Sphyrna tiburo), blacktip shark (Carcharhinus limbatus) and sandbar shark (C. plumbeus) comprised 96.1% of the catch. Canonical correlation analysis (CCA) was used to assess environmental influences on the assemblage of the four common species. Results of the CCA indicated Bonnethead Shark and Sandbar Shark were correlated with each other and with a subset of environmental variables. When the species occurred singly, depth was the defining environmental variable; whereas, when the two co-occurred, dissolved oxygen and salinity were the defining variables. Discriminant analyses (DA) were used to assess environmental influences on individual species. Results of the discriminant analyses supported the general CCA findings that the presence of bonnethead and sandbar shark were the only two species that correlated with environmental variables. In addition to depth and dissolved oxygen, turbidity influenced the presence of sandbar shark. The presence of bonnethead shark was influenced primarily by salinity and turbidity. Significant relationships existed for both the CCA and DA analyses; however, environmental variables accounted for <16% of the total variation in each. Compared to the environmental variables we measured, macrohabitat features (e.g., substrate type), prey availability, and susceptibility to predation may have stronger influences on the presence and distribution of subadult shark species among sites.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Utility of mesohabitat features for determining habitat associations of subadult sharks in Georgia’s estuaries
Series title Environmental Biology of Fishes
DOI 10.1007/s10641-010-9648-3
Volume 88
Issue 4
Year Published 2010
Language English
Publisher Kluwer Academic Publishers
Publisher location Dordrecht
Contributing office(s) Coop Res Unit Atlanta
Description 11 p.
First page 349
Last page 359
Country United States
State Georgia
Online Only (Y/N) N
Additional Online Files (Y/N) N