%0 Journal Article
%T Aerial Survey as a Tool to Estimate Abundance and Describe Distribution of a Carcharhinid Species, the Lemon Shark, Negaprion brevirostris
%A S. T. Kessel
%A S. H. Gruber
%A K. S. Gledhill
%A M. E. Bond
%A R. G. Perkins
%J Journal of Marine Biology
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/597383
%X 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 (¡À8.6) 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. 1. Introduction Aerial survey has been used as a tool to assess species abundance for both terrestrial and marine vertebrates, often where the remoteness or vastness of the survey area and the potentially low abundance of the study species render other techniques uneconomical [1¨C6]. In the marine environment, aerial survey has typically focused on air breathing marine mammals and reptiles [2, 7¨C13] because these taxa are regularly visible at the surface. Through aerial surveys, it has been possible to quantify the abundance of marine creatures in remote locations. A few examples of these are dense concentrations of narwhal (Monodon monoceros) in the offshore pack ice of Baffin Bay, West Greenland [14] and the seasonal distribution of crabeater seals (Lobodon carcinophagus) in the pack ice of Antarctica [15]. In addition, aerial surveys have revealed unique insights into marine creatures, for example, the specific birthing location of an endangered western North Atlantic right whale (Eubalaena glacialis) [16] and mass aggregations of whale sharks (Rhincodon typus), numbering up to 420 individuals, previously not witnessed [17]. For sharks, aerial survey has been largely limited to the large filter feeding species, whale [18¨C20] and basking sharks
%U http://www.hindawi.com/journals/jmb/2013/597383/