Document Type
Article
Abstract
Declines in shark populations have sparked researchers and fishery managers to investigate more prudent approaches to the conservation of these fish. As managers strive to improve data collection for stock assessment, fisheries-independent surveys have expanded to include data-deficient areas such as coastal regions. To that end, a catch series from a nearshore survey off Alabama was combined with data from a concurrent offshore survey with identical methodology to examine the depth use of sharks across the continental shelf (2–366 m). The combined data set contained 22 species of sharks collected from 1995 to 2008: 21 species in the offshore data set (1995–2008) and 12 species in the nearshore data set (2006–2008). Depth was a significant factor determining species’ distributions, primarily for Atlantic sharpnose Rhizoprionodon terraenovae, blacknose Carcharhinus acronotus, and blacktip C. limbatus sharks. Blacknose sharks had the highest catch per unit effort (CPUE) in the middepth stratum (10–30 m), blacktip sharks had consistently higher CPUE in the shallow depth stratum (,10 m), and Atlantic sharpnose sharks showed high abundance throughout both the shallow and mid-depth strata. Length frequency and sex ratio analyses suggest that Atlantic sharpnose and blacknose sharks are using waters greater than 30 m deep for parturition, whereas adult blacktip sharks are probably using shallow waters for parturition. Our abundance patterns illustrate a continuum of depth use across the inner continental shelf. Surveys that do not encompass the entirety of this ecosystem fail to accurately characterize the distributions of these important predators.
First Page
440
Last Page
450
DOI
10.1577/C09-061.1
Publication Date
12-2010
Department
Marine and Environmental Sciences
Recommended Citation
Recommended publisher citation: J. Marcus Drymon , Sean P. Powers , John Dindo , Brian Dzwonkowski & Terry A. Henwood (2010) Distributions of Sharks across a Continental Shelf in the Northern Gulf of Mexico, Marine and Coastal Fisheries, 2:1, 440-450, DOI: 10.1577/C09-061.1
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Comments
This article was published in the journal of Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science from the American Fisheries Society by Taylor and Francis Online.
A link to the online published versions can be found here:
https://www.tandfonline.com/doi/pdf/10.1577/C09-061.1?cookieSet=1
https://afspubs.onlinelibrary.wiley.com/doi/full/10.1577/C09-061.1
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This article is made available under the terms of a Creative Commons Attribution 4.0 International license [CC BY 4.0]