Campbell, G. S., B. A. Bilgre and R. H. Defran. 2002. Bottlenose dolphins (Tursiops truncatus) in Turneffe Atoll, Belize: occurrence, site fidelity, group size and abundance, Aquatic Mammals, 28.2:170-180.
Bottlenose dolphin (Tursiops truncatus) occurrence, site fidelity, group size, and population size were assessed within Turneffe Atoll, Belize, Central America during a 4-year photo-identification study. Five hundred and forty-nine photographic surveys were conducted between March 1992 and March 1996. Dolphin groups were encountered on 83% of surveys, and 2782 dolphins were observed in 732 separate groups. Group sizes (mean = 3.8, SD = 3.55) varied both annually and seasonally. Groups with calves were larger than groups without calves. Eighty-one dolphins were photographically identified, and the majority (81%) of these dolphins were documented by the 150th survey in which one or more identifiable dolphins were successfully photographed (June 1993). Sighting frequencies (mean = 12.2, SD = 14.33) ranged from one to 57, with 20% of the photographed population sighted only once and 37% photographed ≥ 10 times. Dolphins photographed ≥ two times in at least three of the four study years were labeled as residents, and comprised 30% of the identified population. Identified females (n = 16) and males (n = 10) had similar residency patterns. Abundance estimates, derived by using Chao’s Mth closed method, were similar for the first (Mth = 82) and second (Mth = 86) halves of the study. Small group sizes, low abundance estimates and the limited residence pattern observed for dolphins in Turneffe Atoll suggest that they depend on low-density food resources. Governmental and non-governmental concerns over potential human impacts on Turneffe’s marine environment appear to be well placed.
Return to Publications/Theses