US Navy

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Marine Species Monitoring

Bottlenose Dolphin Occurrence in Estuarine and Coastal Waters near Panama City, Florida

Introduction & Objectives

The goals of the proposed study are to determine abundance, habitat use, and distribution patterns of bottlenose dolphins in St. Andrew Bay and adjacent coastal waters in the Naval Surface Warfare Center, Panama City Division, over two seasons.  During fall in the St. Joseph Bay region, the observed 2-3 fold increase in abundance was attributed to Northern Coastal Stock dolphins entering St. Joseph Bay waters.  St. Joseph Bay summer abundance was low and animals sighted during this season were suggested to be representative of the BSE Stock.  Thus, the seasons selected for surveying in SAB are July 2015 (summer) and September 2015 (fall) to determine abundance for the BSE Stock and provide insight into abundance and movements of Northern Coastal Stock dolphins.  Specific study objectives are:

(1)    Identify which marine mammal species occur seasonally within St. Andrew Bay and coastal waters;
(2)    Calculate seasonal resighting rates for individual dolphins and develop a site fidelity index for dolphins in this region to provide baseline data for future studies to assess long-term residence;
(3)    Determine distribution patterns for dolphins within and between SAB and coastal waters;
(4)    Estimate seasonal abundance across the two primary sessions (July and September 2015) and;
(5)    Correlate dolphin presence with particular environmental parameters (e.g. water depth, water temperature, water salinity) and broad habitat types (e.g. shallow bay, channel, sea grass bed, surf zone, open water).

Technical Approach

The study area will include the estuarine waters of St. Andrew Bay, North Bay, West Bay, and East Bay.  The survey area also includes Gulf of Mexico coastal waters directly adjacent to the estuary, extending approximately 3 km offshore, from northwest of Crooked Island Sound (northern boundary of the St. Joseph Bay BSE Stock) to Gulf of Mexico waters adjacent to West Bay.  Capture-recapture photo-id surveys will be conducted during summer (July) and fall (September) of 2015.  For estuarine waters, contour transects (i.e. transects that follow a particular geographic feature) will be followed either 500 m from the shoreline or along the 1 m depth contour (Figure 1).  For coastal waters, contour transects will be followed approximately 3 km off the coastline.   Data will be analyzed to assess seasonal abundance, site fidelity, distribution patterns, and habitat use within the study area.

Progress & Results

Capture-recapture photo-id surveys were conducted during summer (July) and fall (September) of 2015, and spring (April) and fall (October) of 2016.  The total bottlenose dolphins sighted in the four survey sessions are 388, 458, 460, and 551 dolphins, respectively.  In addition, sixty-eight biopsy samples have been collected for contaminant, genetic, and stock structure analyses. The dorsal fin catalog and sighting data from 2015 are available from the Gulf of Mexico Dolphin ID System (GOMDIS) and OBIS-SEAMAP.  A final report for 2015 is also available.  Data entry and photo-ID analysis for the 2016 survey data is currently in progress. The four survey sessions across two years will provide a robust dataset for several manuscripts on topics including abundance, contaminant levels, distribution, habitat use, human interactions, and site fidelity.