Between 2004 and 2007, field surveys were conducted to study bottlenose dolphins (Tursiops truncatus) in the seaside resort of Panama City, Northwest Florida. Using boat-based photo-identification surveys, mark-recapture surveys were performed to estimate the abundance of bottlenose dolphins. According to months, the estimate population size varied between 57 to 178 individuals, with the lowest abundance occurring during the spring. A total of 263 different dolphins were photo-identified. The spatio-temporal distribution of dolphins revealed that animals showed preferred habitat, mainly concentrated in and around the Channel Entrance. Mean group size composed of 5 dolphins, showed significant variations according to the observed zone, the time of the day, and the behaviours of dolphins. Social behaviours were dominant throughout the day Evidence of a feeding peak in the evening was recorded, while playing, sexual and begging were more frequently observed in the afternoon. Using a Geographic Information System (GIS), a foraging hotspot was detected within the study area. Human activities, especially tourism and recreational fishing revealed significant impacts on dolphins behaviours, with several individuals seen to beg regularly close to boats. This unnatural behaviour of begging, were more often observed during the tourism season (between April to August), and occurred mainly near shore the East jetties. Social structure is an important component of the bottlenose dolphin populations. Highly significant differences were found in associations between and within sex classes. Indeed, males associations were stronger than between inter-sexual associations or between females only. Sociogram of males revealed a complex network with strong associations between pairs or trios. The population structure seems to be temporally stable over the study with constant companionship observed in the dolphin population in Panama City. |
