Biology of offshore bottlenose dolphins from east Florida. Final report.

Abstract

This study summarizes aspects of the biology of offshore bottlenose dolphins stranded on the east coast of Florida, using data gathered from 56 animals collected between 1980 and 2000. Results indicated that offshore dolphins strand mostly alive, and are found year-round and throughout the east coast of Florida. The oldest animal examined was 37 years of age. The maximum size attained by an offshore dolphin was 308 cm. The reproductive biology and other life history parameters of east Florida offshore dolphins could not be properly investigated due to the small sample sizes available. Offshore dolphins prey on deep-water species of fish and squid, but may also feed over the continental shelf on coastal species as well. Skull size and selected measurements were useful in distinguishing offshore animals. In contrast, post-cranial characters did not prove as useful. The presence of external and internal parasites and evidence from pelagic predators distinguished a few, but not all animals. Hematological and genetic analyses confirmed the identity of most of the dolphins examined. Diagnosing offshore bottlenose dolphins from strandings can be better accomplished when using several biological tools in combination. It is hoped that results from this study will facilitate the identification of specimens from museum collections and stranding records, and allow for meaningful interpretation of ecological and distributional studies.