Age structure and growth of the bottlenose dolphin (Tursiops truncatus) from strandings in the Mississippi sound region of the north-central Gulf of Mexico from 1986 to 2003

Despite their high abundance and wide distribution, little is known about the historical or current growth and age structure of coastal bottlenose dolphins (Tursiops truncatus) in the north-central Gulf of Mexico. Between 1986 and 2003, teeth were collected from bottlenose dolphins stranded on the mainland coast of Mississippi and the adjacent barrier islands. Bottlenose dolphin strandings occurred year round, peaking in March and April. Neonate strandings also peaked during these 2 mo. Age estimates were obtained from 111 animals by reading the growth layer groups in the dentine layer of the teeth. The ages ranged from < 1 yr to 30 yr of age. The two-stage Laird-Gompertz growth model was fitted to the total length and age data. On the basis of this model, the asymptotic lengths were estimated at 250 cm for females and 255 cm for males. The length at birth estimates were 98-103 cm for females and 100-107 cm for males. These lengths are similar to those of bottlenose dolphin populations from other Gulf of Mexico areas and from the North Atlantic Ocean along the southeastern United States.