Radio-Tracking and Survivorship of Two Rehabilitated Bottlenose Dolphins (Tursiops truncatus) in the Indian River Lagoon, Florida

Despite an increase in the number of stranded dolphins rehabilitated and returned to the wild, the survivorship of these cetaceans is poorly documented. Since rehabilitation and release programs remain limited in scope, the release of dolphins from different age and sex cohorts provides information that is pertinent to protocols for future release candidates. Novel opportunities to track the survivorship of two rehabilitated bottlenose dolphins with radio transmitters occurred in 2001 and 2003 in the Indian River Lagoon (IRL), Florida. Both dolphins were male and had been identified prior to rehabilitation during a photoidentification monitoring program. Dolphin C6 stranded with multiple life-threatening shark wounds in 2000, at age 24, and was released after a successful 6-mo period of rehabilitation. This dolphin re-established an existing male pair-bond with dolphin C7, traveled 67 km from the release site, and survived 100 d before he died from asphyxiation by an exotic fish that lodged in his pharynx. Carter, a calf orphaned in 2003 at 1 y of age, was released following a 3-mo period of care that provided adequate nutrition and weight gain needed for survival in the wild. This young dolphin remained within a 10-km radius of the release site, failed to form a stable relationship with other dolphins, and appeared to have survived only 7 d when radio transmissions from an acoustic tag ceased. These two cases represent the radio-tracking studies of the oldest and youngest known bottlenose dolphins rehabilitated and released in the IRL.