Current Status of Bottlenose Dolphin Populations in the Florida Panhandle
By Douglas Nowacek, PhD, Florida State University
Brian Balmer, MSc Student

Within the past five years, there have been two unusual mortality events in the Florida Panhandle, resulting in over 200 dead bottlenose dolphins.  The single-celled organism responsible for red tide, Karenia brevis, is suspected to be involved in both cases; the degree of involvement in each is still in debate.  This area of the Gulf Coast has had relatively little research performed on its bottlenose dolphin populations.  St.  Joseph’s Bay, the region where the majority of strandings has occurred, was last surveyed by NOAA scientists in 2000, leading scientists to estimate the population of the bay at that time to be zero.  In April and May of 2004, a joint effort between the Sarasota Dolphin Research Program, and the Department of Oceanography at Florida State University spent 11 days surveying and biopsy darting animals in the waters from St. Andrew Sound east to the Ochlocknee Bay.  Animals in the region were seen over a range of habitats, including St. Joseph’s Bay.  A total of 67 biopsy samples was obtained.  The biopsy samples are currently being analyzed genetically to clarify population structure and measure contaminant loads of the sampled animals.

Future research will focus initially on two areas of the eastern end of the Panhandle; St. Joseph’s Bay and Apalachicola Bay-St. George Sound, which are contiguous.  The current plans for St. Joseph’s Bay are to continue intensive surveying and biopsy efforts of the waters inside and outside the bay.  The goals of this research are to determine population structure and an overall population estimate for the region after two mass mortality events.  In April 2005, a capture-release health assessment is planned for St. Joseph’s Bay.  Animals will be sampled similar to protocols established in Sarasota Bay.  Select animals will also have VHF tags attached to their dorsal fins, allowing for radio tracking over the following month.  This work will serve as the basis for Balmer’s Master’s thesis research through the University of North Carolina, Wilmington.

The community structure work is part of a larger effort to study the coastal dolphins of the eastern Panhandle and the ‘Big Bend’ area of Florida.  Nowacek is initiating a photo-identification effort, working in collaboration with the Apalachicola Bay National Estuarine Research Reserve (ANERR).  We will be conducting surveys in the area to address questions such as ‘are the dolphins in this area seasonal or are they year-round residents?’ We will also be investigating the habitat use patterns and foraging ecology of the dolphins in the area.  The last component of this larger study is to sample the acoustic activity and environment of the dolphins.  We will be listening for both dolphin-made sounds as well as any sounds produced by fish in the area.  We know from experiments in Sarasota Bay that dolphins respond strongly to sounds produced by their prey, and we will be documenting the occurrence of fish sounds in this area near the Florida State University Marine Lab.

After this preliminary research, the goal of both SDRP and FSU is to expand research over the entire Florida Panhandle, allowing for definite conclusions about the effects of multiple mortality events on an unknown bottlenose dolphin population.  Funding for this project was provided by NOAA Fisheries through the Chicago Zoological Society.