Residency patterns, seasonality and habitat use among bottlenose dolphins, Tursiops truncatus, in the Cape Romain National Wildlife Refuge, SC

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Peggy E. Sloan (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
Laela Sayigh

Abstract: This study documented the presence of year round and seasonally resident bottlenose dolphins, Tursiops truncatus, in the Cape Romain National Wildlife Refuge near McClellanville, South Carolina, USA. Trends in relative abundance, seasonality and habitat use were determined through monthly systematic photo-identification surveys from September 2003 through August 2005. Dolphins were encountered 445 times and 1,900 individuals were counted during 360 survey hours covering 5,612km. Dolphins were observed within the study site year round. Relative abundance was lowest when sea surface temperatures were below 13oC, increased with temperature, and remained relatively high from March through November. Most sightings occurred in edge habitat, which in this study were salt marsh creeks, intersections and channels surrounded by vegetated salt marsh. Dolphin group size varied significantly in association with surface temperature and habitat use. One hundred and twenty-one individual dolphins, identified by unique dorsal fin characteristics, were sighted between one and 20 times each. Twenty two recognizable individuals used this study site year round, 49 showed seasonal site fidelity, and 50 dolphins were considered transient. All of the identifiable dolphins considered year round residents were sighted exclusively within the salt marsh and never in the open ocean. Some seasonal residents showed strong site fidelity and occurred in the same temperature class over multiple years. Transients, usually sighted only once, were seen most often in the ocean. All dolphins identified interacting with shrimp trawlers were transient. All individually identified dolphins were compared to those maintained in the Mid-Atlantic Bottlenose Dolphin Catalog. Eleven individuals from CRNWR were known from other study sites. Dolphins identified in this study exhibited movement as far north as Wilmington,NC, (n=1), and as far south as Charleston, SC, (n=5). Patterns of seasonal movement displayed by some of these dolphins may reflect their large home ranges or the existence of overlapping communities for some coastal bottlenose dolphins in the South Atlantic Bight. One dolphin in this study also moved between existing Management Units as defined by the National Marine Fisheries Service in their on-going effort to describe stock structure of bottlenose dolphins in the mid-Atlantic. These movements suggest the need to reassess existing management boundaries to better reflect stock structure.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
Language: English
Date: 2009
Keywords
Bottlenose dolphin--Habitat, Bottlenose dolphin--Migration, Bottlenose dolphin--Seasonal variations--South Carolina--Cape Romain National Wildlife Refuge, Bottlenose dolphin--South Carolina--Cape Romain National Wildlife Refuge, Bottlenose dolphin--South Carolina--Cape Romain National Wildlife Refuge--Observations, Bottlenose dolphin--South Carolina--Geographical distribution
Subjects
Bottlenose dolphin -- South Carolina -- Cape Romain National Wildlife Refuge
Bottlenose dolphin -- Habitat
Bottlenose dolphin -- Migration
Bottlenose dolphin -- South Carolina -- Geographical distribution
Bottlenose dolphin -- South Carolina -- Cape Romain National Wildlife Refuge -- Observations
Bottlenose dolphin -- Seasonal variations -- South Carolina -- Cape Romain National Wildlife Refuge