Distribution and Density of Sea Turtles in the Gulf of Mexico (GOM): Gulf of Mexico Marine Assessment Program for Protected Species (GoMMAPPS)

Science Center Objects

The over-arching goal of GoMMAPPS is to collect broad-scale survey data for seabirds, marine mammals and sea turtles to determine distribution and abundance in the Gulf of Mexico.

Areas in the Gulf of Mexico where modeling identified potential habitat

Areas in the Gulf of Mexico where modeling identified potential habitat for Kemp’s ridleys (blue) and loggerheads (red).

The Science Issue and Relevance: The Gulf of Mexico Marine Assessment Program for Protected Species (GoMMAPPS) represents a multi-agency partnership between the Bureau of Ocean Energy Management (BOEM), the United States Fish and Wildlife Service (USFWS), the National Oceanic and Atmospheric Administration (NOAA), and the USGS, all of whom need information on marine vertebrates to provide improved, spatially-explicit density distributions to inform multiple management issues (https://www.boem.gov/GOMMAPPS/). The over-arching goal of GoMMAPPS is to collect broad-scale survey data for seabirds, marine mammals and sea turtles to determine distribution and abundance in the Gulf of Mexico.

As part of the project we will focus on sea turtles to provide information to help BOEM and the Bureau of Safety and Environmental Enforcement (BSEE) assess the risk to sea turtles from various activities associated with energy operations in the GOM. BOEM and BSEE activities may affect loggerhead, Kemp’s ridley, hawksbill, green, and leatherback turtles. In addition to Gulf-wide aerial and vessel-base surveys, satellite tracking and genetic analyses of sea turtles in BOEM’s Western and Central planning areas will provide habitat and population connectivity data on a finer scale.

A nesting loggerhead carrying a satellite tag on the St. Joseph Peninsula, FL

A nesting loggerhead carrying a satellite tag on the St. Joseph Peninsula, FL

Methodology for Addressing the Issue: Sea turtles will primarily be captured in-water by hand, net, or trawling. Adult green turtles will also be tagged on nesting beaches in the northern GOM. Broad scale aerial surveys will be conducted over multiple years to provide information on the seasonal distribution and abundance of sea turtles in U.S. GOM waters. We will model existing satellite tracking and aerial survey data to help guide aerial surveys. This effort will initially use data already in hand and will then be compared to and updated by data gathered as part of GoMMAPPS. Satellite tracking with depth tags will be used to track hard shelled turtles. These data will contribute to the development of accurate abundance estimates, including corrections for aerial survey data, and provide information on use of the water column, movement patterns, behavior, and habitat use for key species and life-stages. Genetic analyses will be used to supplement and fill in gaps from other field data collected during this study to more accurately assess sea turtle abundance and distribution. In addition, these analyses will be used to identify stocks and assess effective population size, genetic diversity, and gene flow.

A large juvenile loggerhead captured in-water in St. Joseph Bay, FL.

A large juvenile loggerhead sea turtle captured in-water in St. Joseph Bay, FL.

Future Steps: We will continue to combine turtle satellite tracking data with NMFS aerial survey data for habitat modeling analyses. We will incorporate data collected from aerial imaging surveys along coastal Alabama, Mississippi, and Louisiana, and satellite tagging along the coasts of Alabama, Mississippi, and Texas. We are developing partnerships with researchers in Texas and Mississippi to build on our efforts, including combining historic datasets, pulling data from additional tags, and performing genetic analyses of individuals tagged throughout the study area.