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 Chukchi and Beaufort Seas for the months of June-October, and extending into Canadian waters of the Beaufort Sea and Amundsen Gulf in August. The models estimate absolute density, rendered as maps of the number of individual animals per 100 km², by statistically correlating sightings reported on aerial line-transect surveys with environmental covariates.

The U.S. surveys were funded by the Bureau of Ocean Energy Management (BOEM) and predecessor agencies. The Canadian surveys were funded by DFO and collaborating organizations. The modeling work led by MGEL was funded by U.S. 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 GIS files and documentation and explore them in an interactive online mapper. In 2017, after we completed our first 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 second modeling cycle in 2020. As with the first cycle, we initiated a collaboration with MML to develop models from MML's Aerial Survey of Arctic Marine Mammals (ASAMM) and its predecessors, commonly known as the Bowhead Whale Aerial Survey Project (BWASP) and the Chukchi Offshore Monitoring in Drilling Area (COMIDA) surveys. At that time, we also expanded the collaboration to include DFO, who contributed aerial surveys of the Canadian Beaufort Sea and Amundsen Gulf. By integrating DFO's surveys with those of ASAMM through 2019, which in 2019 also extended into the Canadian Beaufort Sea and Amundsen Gulf, we were able to expand our modeled area to encompass those seas in the month of August. (Note: only ASAMM surveys from 2019 were available for this project; DFO surveys from 2019 were not available.) We were also able to expand our modeled season to include the month of June. Finally, we were able to expand our taxonomic coverage from 8 taxa in the first iteration to 11 in the second. In addition, for some of the pinnipeds in the second iteration, we prepared separate models for pinnipeds at sea and pinnipeds hauled out. The final predictions covered the period 2000-2019 for the months of June-October. As before, 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

Retired Models

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

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.