Movement patterns of Kemp’s ridley sea turtles in the northwestern Gulf of Mexico 2004-2007

Erin Seney and Andre Landry, Sea Turtle & Fisheries Ecology Research Laboratory, Department of Marine Biology, Texas A&M University at Galveston

The Kemp's ridley sea turtle Lepidochelys kempii is recovering from declines that reduced nesting from a single-day estimate of 10000 to 40000 females in 1947 to <300 during the entire 1985 nesting season. Although beach monitoring is crucial to estimating nesting population size and activity, in-water data are essential for understanding population dynamics, evaluating management strategies, and ensuring the species’ continued recovery. Fifteen immature and 7 adult female ridleys were fitted with platform terminal transmitters and released off the upper Texas coast during 2004 through 2007. Immature individuals were tracked primarily during warmer months and exhibited preferences for tidal passes, bays, coastal lakes, and nearshore waters, although movement patterns varied among years. Females tracked during their inter-­nesting intervals remained in the vicinity of the upper Texas coast and, upon entering the post-nesting stage, moved eastward along the 20 m isobath to foraging areas offshore of central Louisiana. Satellite telemetry indicated that inshore and continental shelf waters of the northwestern Gulf of Mexico serve as developmental, migratory, inter-nesting, and post-nesting habitat for the Kemp’s ridley. Projected population growth will likely lead to increased use of the northwestern Gulf by the species and more frequent encounters with human activities. The extent of such anthropogenic interactions and need for mitigation measures should be examined and considered by natural resource managers to facilitate continued recovery of this and other sea turtle species in the Gulf of Mexico. Likewise, research efforts should be continued to better understand seasonal in-water distributions, abundances, population dynamics, and mortality risks to all life history stages.

The following research objectives were identified:

(1) to characterize movements of benthic-stage im mature and adult female Kemp’s ridleys in the northwestern Gulf of Mexico; and

(2) to identify Kemp's ridley migration patterns and foraging grounds in the northwestern Gulf of Mexico.

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Overview

The dataset contains information necessary to locate the species sightings observed in the survey. The structure of the dataset was defined by NOAA Southeast Fisheries Science Center. Note that the dataset is a subset of the larger, complete dataset collected in the survey which includes environmental information. The columns before LineNo are applied to the shapefile only. The following information is not included in the dataset but will be found in the master data. For details, please contact NOAA Southeast Fisheries Science Center. Track; Speed; GPS Status; Observers; Wind direction; Weather; Sea state; Swell; Visibility; Turbidity; Sunlight; Water depth; Water color; Water temperature; Sighting angle; Effort status.

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	Original ID (created by OBIS-SEAMAP)
tag_id	PTT#
datetime1	Original date/time
obs_date	Date of observation
obs_time	Time of observation
sp_tsn	Species ITIS TSN
sp_obs	Species observed
latitude	Latitude of first position
longitude	Longitude of first position
lat2	Latitude of second position
lon2	Longitude of second position
lc	Location class
iq	Quality indicator
sex	Sex of animal
age_class	Age class of animal (adult or juvenile)
body_size	SCL (in cm)
country	Country animal was tagged
beach_name	Beach name animal was tagged
notes	Notes on animal
cite1	Citation 1
cite2	Citation 2