Association Patterns of Bottle-Nosed Dolphins (Tursiops-Truncatus) in Galveston Bay, Texas

Resightings of photographically identified bottlenose dolphins (Tursiops truncatus) were used to calculate association indices for a population of free-ranging individuals occurring in the Galveston Bay system, Texas, and the adjacent Gulf of Mexico. Thirty-five individual dolphins with four or more sightings per year were included in the analyses to ensure likelihood of identification and comparability in 1990 and 1991. The patterns of association were weak, with few strong associations between individuals. The average association indices for 1990 and 1991 were similar; however, the magnitude of individual association indices changed drastically between the years. The low number of detectable, long-term affiliations indicates high group fluidity