Tursiops truncatus ssp. gephyreus, Lahille's Bottlenose Dolphin

Abstract

Lahille's Bottlenose Dolphin, a subspecies of the Common Bottlenose Dolphin (Tursiops truncatus), occurs in low numbers only in southern Brazil, Uruguay and Argentina. Lahille?s Bottlenose Dolphins are mainly resident to localized areas and restricted to coastal habitat resulting in a vulnerability to increasing pressures from human activities. Bycatch, pollution and prey depletion are the main known threats to the subspecies. There is evidence that the subspecies is declining in at least part of its range due to bycatch in fisheries and other unknown factors, although robust data on population dynamics is limited. Genetic variability of the subspecies is low at both nuclear and mtDNA markers. The abundance of Lahille's Bottlenose Dolphins has been estimated for most parts of the subspecies´ range. The sum of available abundance estimates suggests a maximum total population size of 600 individuals. With an estimated 60% of mature individuals (Taylor et al. 2007), the total number of mature individuals in the subspecies can be estimated at 360, well below the threshold to be listed as Vulnerable under criterion D1.