Experimental Return to the Wild of Two Bottlenose Dolphins

Kim Bassos-Hull and Randall S. Wells
Chicago Zoological Society, c/o Mote Marine Laboratory, 1600 Thompson Parkway, Sarasota, FL 34236

In the first scientific experiment of its kind, two young male bottlenose dolphins (Tursiops truncatus) were captured in Tampa Bay, Florida, and then as planned, returned to the wild at the same locale in October 1990, after two years in captivity. There has been 69 sightings of one dolphin through April 1999 and 52 sightings of the other dolphin through July 2000. Observations of each dolphin have shown them to be fully integrated into the local dolphin societies.

One objective of this project was to test and determine appropriate methodology for returning cetaceans to the wild. This need was recognized since several species of small cetaceans are facing imminent extinction and may need to be involved in captive breeding and reintroduction programs. Some of the factors identified in the success of this project were: (1) selection and release of a functional social unit typically found in the wild, (2) selection and release of subadult dolphins already independent of their mothers, (3) short duration in captivity, and (4) return to their original collection site to provide familiarity with habitat and social structure features.

Another objective was to document the behavior of the two released dolphins for comparison with other dolphins in the area. This was considered crucial to be able to determine a successful reacclimation to the wild. They displayed typical behavioral, ranging, and social association patterns during the initial crucial months and over the longer term.