Abstract

The U.S. Navy is responsible for compliance with a suite of U.S. federal environmental and natural resources laws and regulations that apply to the marine environment, including the Marine Mammal Protection Act (MMPA) and the Endangered Species Act (ESA). Under U.S. law, the Navy must periodically prepare an Environmental Impact Statement (EIS) that estimates the potential impacts of proposed naval training and testing activities on marine mammal populations. This requires a detailed understanding of the spatiotemporal distributions of these populations.

To facilitate this, government organizations such as the National Marine Fisheries Service (NMFS/NOAA Fisheries) have conducted visual line-transect surveys of marine mammals for over 35 years, resulting in various studies that estimated the abundance, density, and distributions of marine mammal populations. Using a method known as density surface modeling (Hedley and Buckland 2004; Miller et al. 2013), these data may be linked with ecologically-relevant covariates such as sea surface temperature to develop statistical models that estimate density from the covariates. The models can then be predicted across maps of covariates obtained from remote sensing and ocean modeling to produce maps of marine mammal density.

For the "Phase IV" EIS for the Atlantic Fleet Training and Testing (AFTT) study area, the Navy funded Duke University Marine Geospatial Ecology Lab (MGEL) to develop density surface models for the extant marine mammals. The Phase IV models updated the Phase III models we completed 7 years earlier, using the same overall methodology (Mannocci et al. 2017). For the Phase IV analysis, our collaborators collectively contributed over 3.2 million linear kilometers of line-transect survey effort—nearly 3 times that of the Phase III analysis—collected across 1992-2020, from which we built density surface models for 29 cetacean and 1 pinniped taxa. The Phase IV methodology and results are documented by a summary report to the Navy (Roberts et al. 2023), as well as taxon-specific reports that documented the details of each model.

The AFTT models are distinct from the East Coast (EC) and Gulf of Mexico (GOM) models that were also updated in 2022, and are mainly intended for use beyond the geographic extents of the EC and GOM models. To estimate densities for the areas beyond the EC and GOM, where there was very little survey data available to us, we developed parsimonious models designed to produce plausible extrapolations of marine mammal density.

Within the extents of EC and GOM models, we recommend that those models be used instead. Please see Roberts et al. 2023 for a detailed explanation of the different models. If you plan to use the AFTT models in science or management application, we recommend you consult with us first.

This website allows you to download the density maps predicted by each AFTT model in GIS-compatible raster format along with maps that estimate the statistical uncertainty in the density estimates. Included with the maps are taxon-specific reports that provide diagnostic maps, plots, and statistical output for each taxon along with brief discussion of modeling decisions and the results.

Citation

When citing our methodology or results generally, please cite Roberts et al. 2023 and Mannocci et al. 2017. When citing a specific model, please see the reference listed in its taxon-specific report or README.txt file.

Downloads

Download specific results below or all rasters, maps, and supplemental reports together here (1.5 GB).

Supplemental Report: Estuarine Bottlenose Dolphins

We evaluated current and past research on bottlenose dolphins for 35 strata (distinct areas of interest defined by the US Navy) that have been identified within estuarine waters: 22 strata within 6 regions along the US east coast (EC), Atlantic Ocean and 13 strata within 9 regions along the US Gulf of Mexico (GOM) coast. We noted the common bottlenose dolphin population stock in the area, compiled potential sources of information, determined the data source that was the best available to estimate density and uncertainty, included the methods for calculations, and summarized the results with a brief discussion. Final results and geospatial data products for all estuarine strata were delivered to the US Navy within the Marine Species Density Database (NMSDD), as part of the Phase IV marine mammal density modeling updates for the US Navy's Atlantic Fleet Training and Testing (AFTT) study area. The stand-alone final report on estuarine common bottlenose dolphins supplements the US Navy Phase IV NMSDD geospatial data products and final report for all marine mammal species.

Acknowledgements

First of all, we thank the numerous scientists, observers and crews who collected and shared cetacean observations with us; thank you for the opportunity to analyze the data you produced. Debi Palka, Tim Cole, Christin Khan, and colleagues contributed the NOAA Northeast Fisheries Science Center surveys. Lance Garrison, Keith Mullin, and colleagues contributed the NOAA Southeast Fisheries Science Center surveys. Amy Whitt, Suzannes Bates, and Gary Buchanan contributed surveys from the New Jersey Department of Environmental Protection Ocean/Wind Power Ecological Baseline Study. Susan Barco and Gwen Lockhart contributed the Virginia Aquarium and Marine Science Center surveys, in partnership with Rob DiGiovanni Jr. of the Atlantic Marine Conservation Society (previously of Riverhead Foundation for Marine Research and Preservation) and the Maryland Department of Natural Resources. Bill McLellan, Ann Pabst, and colleagues contributed the University of North Carolina Wilmington surveys. Scott Kraus, Orla O'Brien, Jessica Redfern, and Ester Quintana-Rizzo contributed surveys from New England Aquarium. Tim Gowan and Katie Jackson contributed surveys from Florida FWC/FWRI. Melanie White contributed surveys from Clearwater Marine Aquarium Research Institute and predecessor organizations. Megan Rickard, Ann Zoidis, and Kate Lomac-McNair contributed surveys conducted by New York State Department of Environmental Conservation and TetraTech, Inc. Mark Cotter contributed surveys from HDR, Inc. Phil Hammond, Claire Lacey and colleagues contributed the Small Cetacean Abundance in the North Sea and Adjacent waters II (SCANS-II) and Cetacean Offshore Distribution and Abundance in the European Atlantic (CODA) surveys. Odd Aksel Bergstad, Thomas de Lange Wenneck, Leif Nøttestad, and Gordon Waring contributed the MAR-ECO survey. Vincent Ridoux and colleagues contributed surveys from the REcensement des Mammifères marins et autre Mégafaune pélagique par Observation Aérienne (REMMOA) and Suivi Aérien de la Mégafaune Marine (SAMM) programme. Oliver Boisseau and colleagues contributed surveys from R/V Song of the Whale conducted by Marine Conservation Research.

Funding for this project was provided by U.S. Fleet Forces Command and was managed on their behalf by Naval Facilities Engineering Systems Command Atlantic.

Certain data contributors requested that their programs or products be acknowledged in a specific way. We include these acknowledgements below.

Virginia Aquarium & Marine Science Center's Virginia CZM Wind Energy Area Surveys were funded by the Virginia Coastal Zone Management Program at the Department of Environmental Quality through Task 1 of Grant NA12NOS4190027 and Task 95.02 of Grant NA13NOS4190135 of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, under the Coastal Zone Management Act of 1972, as amended. The University of North Carolina Wilmington's Navy surveys were funded by U.S. Fleet Forces Command. University of North Carolina Wilmington's right whale surveys were funded by NOAA. New England Aquarium's surveys of the Massachusetts and Rhode Island Wind Energy Areas, known in this report as the NLPSC and MMS-WEA programs, were funded by Massachusetts Clean Energy Center and the Bureau of Ocean Energy Management. Odd Aksel Bergstad, Thomas de Lange Wenneck, Leif Nøttestad, and Gordon Waring contributed the MAR-ECO survey under the Norwegian License for Open Government data (NLOD). The REMMOA and SAMM surveys were contributed by Observatoire PELAGIS at the University of La Rochelle, France.

Funding for the development of HYCOM has been provided by the National Ocean Partnership Program and the Office of Naval Research. Data assimilative products using HYCOM are funded by the U.S. Navy. The 1/12 degree global HYCOM+NCODA Ocean Reanalysis was funded by the U.S. Navy and the Modeling and Simulation Coordination Office. Computer time was made available by the DoD High Performance Computing Modernization Program. The output is publicly available at https://hycom.org. The Ssalto/Duacs altimeter products were produced and distributed by the Copernicus Marine and Environment Monitoring Service (CMEMS) (https://marine.copernicus.eu). The altimetry and the Mesoscale Eddy Trajectory Atlas products were produced by Ssalto/Duacs and distributed by AVISO+ (https://www.aviso.altimetry.fr) with support from CNES, in collaboration with Oregon State University with support from NASA. CCMP vector wind analyses are produced by Remote Sensing Systems. Data are available at https://www.remss.com. This study has been conducted using E.U.Copernicus Marine Service Information, including SEAPODYM (doi: 10.48670/moi-00020) and Copernicus GlobColour (CMEMS product code OCEANCOLOUR_GLO_CHL_L4_REP_OBSERVATIONS_009_082).

Conflict of interest statement

As acknowledged above, U.S. Fleet Forces Command was one of the funders of this modeling project. The Navy was given the opportunity to suggest spatial, temporal, and taxonomical resolutions and a geographic extent that would facilitate the Navy's use of the results in U.S. environmental regulatory processes. When the analysis was complete, the Navy was given opportunity to view preliminary results. Neither the Navy nor any other funder participated in the analysis of the data or the preparation of the manuscript.