Abstract
Florida Bay is a shallow, subtropical estuary that is open to the Gulf of Mexico but contains geological features such as mangrove islands that limit water circulation. Previous studies have suggested that bottlenose dolphins (Tursiops truncatus) inhabit this Florida Bay estuary yearround as resident populations. To learn more about these populations, ongoing photoidentification efforts by Dolphin Research Center (DRC) have been focused on both Florida Bay and the Eastern Atlantic Ocean side from Islamorada to Marathon. This project explored the distribution of bottlenose dolphins in Florida Bay using photo-identification efforts conducted by DRC using the Gulf of Mexico Dolphin Identification System (GoMDIS) database. This project explored the hypothesis of a high resighting of bottlenose dolphins occupying the waters within the study area over multiple years and assessed which individuals are residents and their level of residency through photo-identification. This project also utilized an unmanned aerial system (UAS) to collect aerial photographs of free-swimming bottlenose dolphins in Florida Bay to assist in the photo-identification of individuals as well as analysis of body condition and measurement of body length. Aerial photographs were analyzed using an updated beta version of the program MorphoMetriX, and body length, body width, and a body condition score (BCS) were calculated. All dolphins analyzed in MorphoMetriX were found to have body condition scores of 3 (normal) or 4 (robust), with a large variance between length and width but overall similar length to width ratios. A correlation test between length and width also indicated a moderate and significant positive linear relationship. Six dolphins have been sighted more than ten times since DRC’s photo-identification study began in 2013 and are likely long-term residents. Dolphins that have been sighted once every few years could be residents of Florida Bay but perhaps spend most of their time in Everglades National Park waters, where drone flights are currently prohibited. Overall, this study provided valuable baseline information about the habitat use of coastal dolphins in Florida Bay and helped assess site fidelity and body condition for this population.