A preliminary study of allozyme differences amongst Carcharhinus sharks from the continental slope near Abidjan, Côte d\'Ivoire

Abstract

Genetic variability of fifty-five shark specimens from the genus Carcharhinus was analysed using 18 allozyme loci. Sixteen loci were polymorphic either within, or between, species. Levels of genetic polymorphism, as measured by observed heterozygosity values, ranged from 0.008 (±0.008) to 0.056 (±0.038). Nei's (1978) genetic distances between Carcharhinus species ranged from 0.235 to 0.784. Morphological identification, using keys, classified them as members of four morphological groups, corresponding to four species: Carcharhinus signatus, C. brevipinna, C. longimanus and C. limbatus. Genetic data confirmed that the first three species were correctly identified, but that the C. limbatus individuals could be further divided into two clearly-differentiated groups, one of which is probably C. limbatus, whereas the other could either be misidentified or be a new taxon.

Keywords: allozyme differentiation, fixed allele differences, genetic variation, sharks, species identification, West Africa

African Journal of Aquatic Science 2007, 32(3): 305–310