Community structure and abundance of bottlenose dolphins Tursiops truncatus in coastal waters of the northeast Gulf of Mexico

Reny Tyson, Duke University
Brian Balmer, Chicago Zoological Society, c/o Mote Marine Laboratory

We examined bottlenose dolphin Tursiops truncatus community structure and abundance in the northeast Gulf of Mexico coastal waters stretching from St. Vincent Sound to Alligator Harbor, Florida, USA. Photographic-identification surveys were conducted between May 2004 and October 2006 to gain an understanding of dolphin distribution in this region. Dolphins were distributed year-round throughout the region; however, individual sighting records indicate that 2 parapatric dolphin communities exist. We conducted mark-recapture surveys using photographic-identification techniques to estimate the abundance of dolphins inhabiting the 2 areas these communities reside in: St. Vincent Sound/Apalachicola Bay, western; and St. George Sound/Alligator Harbor, eastern. Sighting records of individual dolphins from 2004 to 2008 support the existence of 2 communities in these areas; only 3.5% of distinctive dolphins photographed were seen in both western and eastern areas. The 2 communities differ in their structure: the eastern area supports a more transient population with 45.7% of distinctive dolphins photo graphed only once compared with 28.3% in the west. Independent estimates of abundance (N, 95% CI = [low, high]) were calculated using the Chapman modification of the Lincoln-Petersen method for June 2007 and for January and February 2008 for the eastern area (242 [141−343], 395 [273−516]) and for the western survey area (197 [130−264], 111 [71−150]), respectively. Our results serve as a baseline that can be used by the US National Marine Fisheries Service to manage bottlenose dolphins in this region.

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[2015-03-24] A few records had a wrong animal count of zero. The value is replaced with a blank representing species presence only.

Overview

This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downloadable online. Other attributes may be obtained upon provider's permission.

Attributes in dataset

Attribute (table column)	Description
oid	Unique ID number (generated by OBIS-SEAMAP)
obs_date	date of observation
sighting	Sighting #
timebegin	The time sighting begins - string format
obs_time	The time sighting begins
timeend	The time sighting ends
latitude	Latitude in decimal degrees at the begining
longitude	Longitude in decimal degreesat the begining
end_lat	Latitude in decimal degrees at the end
end_long	Longitude in decimal degreesat the end
sp_obs	Species name
sp_tsn	ITIS taxonomic serial number. This field added by OBIS-SEAMAP
obs_count	# of animals, best estimate
bestcalves	# of calves, best estimate
bestyoy	# of yoy, best estimate
program	Program name
vessel	Vessel name
geom	Geometry field added by OBIS-SEAMAP