Sea Turtle Habitat Use in the Chesapeake Bay
Satellite telemetry is a technique that allows researchers to track the movement of an animal by using satellites to detect signals emitted from a transmitter attached to the animal. Since 2011 the Research & Conservation arm of the Virginia Aquarium & Marine Science Center has been tagging and tracking sea turtles in this manner for a number of research initiatives. Transmitters, or "tags" are safely secured to the carapace (top shell) of sea turtles, and extensive data is collected that allows researchers to more clearly understand their behavior and migratory movements.
Most recently Aquarium Scientist Sue Barco along with Gwen Lockhart, formerly with the Aquarium, partnered with sea turtle researcher Andrew Di Matteo, an expert in mapping and modeling, to examine how loggerhead and Kemp's ridley sea turtles use the Chesapeake Bay. While these two species share a common diet, primarily, true crabs and horseshoe crabs, what was discovered was that the two species actually foraged in different and distinct areas while visiting the Bay seasonally. This observation is significant because it means loggerheads and Kemp's ridley turtles are less likely to compete with each other for food supplies. According to the mapping model this team developed as a result of tracking data, loggerheads are more likely to be found in deeper water closer to the center of the Bay, and Kemp's ridley turtles prefer shallower water, closer to shore and in the lower portion of major rivers (see maps below).
Number of total habitat days (A) and important habitat (B) for loggerhead turtles (left two maps) compared with Kemp’s ridley turtles (right two maps) using a randomly generated pseudo-absence model. Black dots on the important habitat maps (B) are modeled locations generated from telemetry data. *
This work, conducted using tagging data collected by Aquarium scientists and their colleagues, is the first comprehensive analysis of telemetry data comparing the two species in Virginia. Results of the project have been reported to the U.S. Navy's Marine Species Monitoring Program and plans to submit the report as a scientific publication are underway. It is our hope that these analyses will be used by protected species managers in Virginia, by the Department of Wildlife Resources, and nationally, by NOAA Fisheries to designate foraging habitat for these two species and more efficiently manage and conserve sea turtles in the Chesapeake Bay.
Important conservation work like this is made possible only through grants and generous private financial support. The first major grant received by our scientists was from the National Ocean Service (NOS) for its Recovery Grants to States Program which supported research and management of protected marine species. The match required for the NOS grant was provided by the Aquarium's Batten Research Endowment. This large, multi-year project was followed by a series of contracts from the U.S. Navy's Fleet Forces Command, managed by Naval Facilities Engineering Command Atlantic as part of the U.S. Navy's Marine Species Monitoring Program. This funding and the private financial support allow Aquarium researchers to amass a significant data set of sea turtle movements in the Chesapeake Bay and Atlantic Ocean. The data have been used in several published scientific papers authored by Aquarium staff and collaborators (see list of papers below).
Recent scientific papers, date of publication, and authors that used Aquarium sea turtle telemetry data:
- Estimating the distribution and relative density of satellite-tagged loggerhead sea turtles using geostatistical mixed effects models (2018) by Megan V. Winton, Gavin Fay, Heather L. Haas, Michael Arendt, Susan Barco, Michael C. James, Christopher Sasso, Ronald Smolowitz
- Loggerhead turtles are good ocean-observers in stratified mid-latitude regions (2018) by Samir H.Patel, Susan G.Barco, Leah M.Crowe, James P.Manning, EricMatzen, Ronald J.Smolowitz, Heather L.Haas
- Loggerhead turtle (Caretta caretta) density and abundance in Chesapeake Bay and the temperate ocean waters of the southern portion of the Mid-Atlantic Bight (2018) by Susan G. Barco, M. Louise Burt, Robert A. DiGiovanni Jr., W. Mark Swingle, Amanda S. Williard
- Normalizing home ranges of juvenile Kemp's ridley turtles (Lepidochelys kempii) in an important estuarine foraging area to better assess their spatial distribution (in review) by Andrew DiMatteo, Gwen Lockhart, Susan Barco
*Referenced from: DiMatteo, A., S. Barco, and G. Lockhart. 2020. Loggerhead and Kemp’s Ridley Sea Turtle Habitat Models for the Chesapeake Bay. Prepared for U.S. Fleet Forces Command. Submitted to Naval Facilities Engineering Command Atlantic, Norfolk, Virginia, under Contract No. N62470-15-D-8006 Task Orders 17F4031, 19F4026, and 20F4039, issued to HDR, Inc., Virginia Beach, Virginia. August 2020.