Use of a fishery-independent trawl survey to evaluate distribution patterns of subadult sharks in Georgia

Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science
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Abstract

We investigated the utility of a fishery-independent trawl survey for assessing a potential multispecies shark nursery in Georgia's nearshore and inshore waters. A total of 234 subadult sharks from six species were captured during 85 of 216 trawls. Catch rates and size distributions for subadult sharks and the ratio of neonates to juveniles were consistent among areas. The highest concentrations of subadult sharks occurred in creeks and sounds. Species composition varied among areas. The Atlantic sharpnose shark Rhizoprionodon terraenovae was the most abundant species in sound and nearshore stations, whereas the bonnethead Sphyrna tiburo was the most abundant species in creeks. The aggregate of other species occurred with higher frequency in the sounds and nearshore. Sampling characteristics of the trawl survey were compared with those from a fishery-independent longline survey of subadult sharks to assess the similarity of the two gears. A total of 193 subadult sharks from seven species were captured during 57 of 96 longline sets, whereas 52 subadults from four species were captured during 20 of 48 trawls. Selectivity and efficiency differed between the two gears. The trawl had lower catch rates, caught smaller sharks, and encountered a different suite of species than the longline. General seasonal trends in relative abundance also differed between the two gears; the longline showed an increasing trend in abundance, whereas the trawl showed a stable trend. Although trawls were not found to be efficient for sampling subadult sharks from most species, they can be a useful source of supplemental data.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Use of a fishery-independent trawl survey to evaluate distribution patterns of subadult sharks in Georgia
Series title Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science
DOI 10.1577/C08-019.1
Volume 1
Issue 1
Year Published 2009
Language English
Publisher American Fisheries Society
Publisher location Bethesda, MD
Contributing office(s) Coop Res Unit Atlanta
Description 12 p.
First page 218
Last page 229
Online Only (Y/N) N
Additional Online Files (Y/N) N