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Journal of Marine Biology
Volume 2013, Article ID 597383, 10 pages
http://dx.doi.org/10.1155/2013/597383
Research Article

Aerial Survey as a Tool to Estimate Abundance and Describe Distribution of a Carcharhinid Species, the Lemon Shark, Negaprion brevirostris

1School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK
2Bimini Biological Field Station, 15 Elizabeth Drive, South Bimini, Bahamas
3University of Windsor, Great Lakes Institute for Environmental Research, 401 Sunset Avenue, Windsor, ON, Canada N9B 3P4

Received 23 April 2013; Revised 6 August 2013; Accepted 2 September 2013

Academic Editor: Susumu Ohtsuka

Copyright © 2013 S. T. Kessel et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Aerial survey provides an important tool to assess the abundance of both terrestrial and marine vertebrates. To date, limited work has tested the effectiveness of this technique to estimate the abundance of smaller shark species. In Bimini, Bahamas, the lemon shark (Negaprion brevirostris) shows high site fidelity to a shallow sandy lagoon, providing an ideal test species to determine the effectiveness of localised aerial survey techniques for a Carcharhinid species in shallow subtropical waters. Between September 2007 and September 2008, visual surveys were conducted from light aircraft following defined transects ranging in length between 8.8 and 4.4 km. Count results were corrected for “availability”, “perception”, and “survey intensity” to provide unbiased abundance estimates. The abundance of lemon sharks was greatest in the central area of the lagoon during high tide, with a change in abundance distribution to the east and western regions of the lagoon with low tide. Mean abundance of sharks was estimated at 49 (±8.6) individuals, and monthly abundance was significantly positively correlated with mean water temperature. The successful implementation of the aerial survey technique highlighted the potential of further employment for shark abundance assessments in shallow coastal marine environments.