Abstract

The Duke Marine Geospatial Ecology Laboratory (MGEL), in collaboration with the National Oceanic and Atmospheric Administration's (NOAA's) Marine Mammal Laboratory (MML), based at NOAA's Alaska Fisheries Science Center, and with Fisheries and Oceans Canada (DFO), developed a collection of marine mammal density surface models spanning United States (U.S.) waters of the Bering, Chukchi and Beaufort Seas for the months of June-October, extending into Canadian waters of the Beaufort Sea and Amundsen Gulf in August, and Russian waters for most species. The models estimate absolute density, rendered as maps of the number of individual animals per 100 km², by statistically correlating sightings reported on aerial and shipboard line-transect surveys with environmental covariates.

The U.S. surveys were funded by the Bureau of Ocean Energy Management (BOEM) and the North Slope Borough (NSB) and predecessor agencies. The Canadian surveys were funded by DFO and collaborating organizations. The modeling work led by MGEL was funded by United States Fleet Forces Command (USFF) of the U.S. Navy and was managed on their behalf by Naval Facilities Engineering Systems Command Atlantic (NAVFAC LANT). The purpose of the project was to develop the data needed by the Navy to comply with U.S. laws that require the assessment of potential impacts to protected marine species resulting from military readiness activities. All marine mammals in the U.S. are protected under the Marine Mammal Protection Act (MMPA), and some marine species receive additional protection under the Endangered Species Act (ESA). As stipulated by the MMPA and ESA, information on the potential location and numbers of protected marine species is required in order to estimate how many animals might be affected by a specific activity. The Navy performs quantitative analyses to estimate the number of marine mammals that could be affected by at-sea training and testing activities. A key element of this quantitative impact analysis is knowledge of the abundance and density of the species in specific areas where those activities will occur. The density surface models archived here provide that information.

This page lists the latest available models and provides links to download their Geographic Information System (GIS) files and documentation and explore them in an interactive online mapper. In 2020, after we completed our second iteration of density surface models for the Navy, USFF, and NAVFAC LANT, they contracted us to prepare updated models using the latest available survey data and modeling methodology. We completed this third modeling cycle in 2026. As with the first and second cycles, we initiated a collaboration with MML to develop models from the long-term Aerial Survey of Arctic Marine Mammals (ASAMM) program conducted by NOAA MML, supplemented by surveys in the Canadian Beaufort Sea and Amundsen Gulf conducted by DFO. Additionally, we added survey data from 2 shipboard MML surveys, ARCWEST and CHAOZ that took place in the Bering and Chukchi seas (2010-2016). Notable changes in this modeling cycle include an expansion of the study area into the Bering Strait, the use of additional dynamic and static covariates in models, the addition of a killer whale model, and a change in Beluga models to designate two stock-level models for beluga whales: one for the Beaufort (B) and Eastern Chukchi (EC) sea stocks, and another for the Eastern Bering (EB) stock in Norton Sound. The final predictions covered the period 2008-2021 for the months of June-October, except for the EB beluga stock which was modeled for only June in 2017 when it was presumed the entire stock was present in Norton Sound (M. Ferguson pers comm). As before, for all other models we summarized the predictions into climatological grids giving mean density for each month across all years.

Model resolution and units

All models have a spatial resolution of 10 km. Model outputs are given as GIS-compatible raster files in an Albers Equal Area projection with a cell size of 10x10 km. The unit of density is individuals / 100 km². Therefore, the raster values also represent the number of individuals per grid cell. To convert to individuals / 1 km², divide the raster values by 100.

Downloads

• To download all models in a single zip file, click here (290MB). All documentation is included in that zip, as well as the individual taxon zips below

Reports

• Updated Marine Species Density Models for the Arctic Study Area. Final Report

Retired Models

These models have been retired and replaced by more recent models listed above. They are retained here for reference purposes.

Acknowledgments

This project would not be possible without the contributions of many individuals and organizations. Above all, we acknowledge the work of those who collected, processed, and shared marine mammal and covariate data with us, and to those who funded the production of those data. In particular, we thank the observers, pilots, ship captains, and crew who collected the marine mammal observations that form the core of this analysis. The logos of these organizations appear at the top of this page and they are named within our project report. Thank you all for the opportunity to analyze the data you produced; we hope you find this project a satisfactory outcome of your efforts.

Many thanks to colleagues who shared data, reviewed portions of our work, provided valuable advice, or answered technical questions, including: Catherine Berchok, Laura Busch, Christy Cowan, Jessica Crance, Monica DeAngelis, Andrew DiMatteo, Joseph Fayton,  Megan Ferguson, Jessica Greene, Lois Harwood, Chris Jenkins, Danielle Jones, Rhianna Knerr, Marianne Marcoux, Kevin Nelson, Emily Robinson, Sean Scannell, and Laura Sparks.

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

Conflict of Interest Statement

U.S. Fleet Forces Command was the principal funder 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. The Navy did not participate in the analysis itself.