Data gaps for marine turtles exist throughout the Gulf of Mexico (GOM). However, some of the biggest gaps in our knowledge of marine turtle ecology occur in areas of heavy oil and gas activity, which includes BOEM (Bureau of Ocean Energy Management) Central and Western Planning Areas. This project will focus significant field efforts on those two regions, while analyzing broad-scale data from across the entire GOM. Basic information on abundance, distribution, and movement patterns of sea turtles are lacking in this geographic area, and this gap has implications for various BOEM and BSEE (Bureau of Safety and Environmental Enforcement) activities including oil spill risk analysis, decommissioning of oil platforms, and movements of vessels.
Routine activities and accidental, unexpected events associated with Outer Continental Shelf (OCS) oil and gas activities in the northern GOM have the potential to impact sea turtles. These impacts have the potential to range from mild to lethal. BOEM using its Oil Spill Risk Analysis (OSRA) model to estimate the probability of an oil spill occurring and then encountering sea turtle habitat. The OSRA model is informed by the best available information of the abundance of protected species both spatially and temporally.
The overall intent of GoMMAPPS is to conduct broad-scale surveys for protected species to inform the distribution and abundance of marine animals across years and seasons. This information will help BOEM and BSEE assess the risk of various activities associated with marine minerals resources to sea turtles. GoMMAPPS represents a multi-agency partnership between BOEM, USFWS (United States Fish and Wildlife), NOAA (National Oceanic and Atmospheric Administration), and USGS (US Geological Survey), all of whom desire information for large marine vertebrates to provide improved spatially-explicit density distributions to inform multiple management issues.
Broadscale aerial surveys will be conducted by partners at the NOAA National Marine Fisheries Service (NMFS) over multiple years to provide information on the seasonal distribution and abundance of sea turtles in U.S. GOM waters. USGS personnel are currently working with NMFS personnel to arrange data collection logistics including methods of documenting turtles during surveys and parameters recorded. Aerial surveys will be designed to capture seasonal variability and will be coordinated with NOAA for the offshore surveys and USFWS for the nearshore surveys. Trained NMFS observers will conduct the offshore surveys. An aerial imaging system will be attached to the USFWS aircraft to capture images every second. When feasible, surveys will include the collection of relevant physical and biological data to support habitat and ecological modeling.
At the start of the project, modeling will be conducted using existing USGS satellite tracks and previously flown NOAA aerial survey data to help guide future aerial surveys. This effort will allow for initial habitat modeling using data in-hand prior to the start of GoMMAPPS field work. First year modeling will be compared to and updated by data gathered as part of GoMMAPPS and related programs. This task will also include spatial analyses of new survey and tracking data collected during the project.
Tracking tags will be used to track hard-shelled turtles (loggerheads, Kemp’s ridleys, green turtles) captured in-water at various locations in the GOM. A proportion of location-only tags and dive-capable tags will be used at each site. Location-only tags allow for longer tracking times which provide us with information on seasonal movements; dive-capable tags, which typically track for shorter periods (due to battery constraints), and provide us with necessary information on depth use by individuals. Using dive-capable satellite tags will allow us to characterize dive profiles for turtles throughout the year. These data can provide BOEM and partners with information to better understand turtle use of the water column during dredging activities, risk of entrainment in dredges, and use of oil/gas platforms. Dive data can also be used to correct the data collected during the aerial surveys. Sites for tagging will be located primarily in the northern and western GOM extending from Pensacola, FL to Padre Island, TX, which is the most active region for offshore oil and gas activity.
During tagging efforts, biological samples, including blood, skin, and carapace, will be collected from captured turtles for genetic analyses. Genetic analyses will be used to identify stocks, and assess effective population size, genetic diversity, and gene flow.
Habitat modeling will be conducted on previously collected data held by USGS (satellite tracking) and NMFS (aerial surveys) and data collected during this project. In addition, home range analyses will be conducted with the tracking data.