![]() ![]() These models estimate density as a continuous function of habitat variables (e.g., sea surface temperature, seafloor depth, etc.) and thus allow predictions of species densities on finer spatial scales than traditional design-based line-transect analysis methods, which generally provide a single estimate of species density for a broad geographic area. Species distribution models are now widely used in conservation and management to predict suitable habitat for protected marine species and to assess risks of effects from human activities. A key element of this quantitative impact analysis is knowledge of the abundance and concentration (density - the number of individual animals found per square kilometer of area) of the species in specific areas where those activities will occur. The Navy performs quantitative analyses to estimate the number of marine mammals and sea turtles that could be affected by at-sea training and testing activities. 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 that might be affected by a specific activity. All marine mammals in the United States are protected under the MMPA, and some species receive additional protection under the ESA. Navy takes responsibility for reviewing and evaluating the potential environmental impacts of conducting at-sea training and testing operations. ![]() To ensure compliance with United States regulations including the Endangered Species Act (ESA), the Marine Mammal Protection Act (MMPA), the National Environmental Policy Act (NEPA), and Executive Order (EO) 12114 (Environmental Effects Abroad of Major Federal Actions), the U.S. Density maps and GIS-compatible rasters may be downloaded below. Survey transects are shown in light gray, and black dots are sighting locations. Model-based densities within the central North Pacific study area for rough-toothed dolphin (Steno bredanensis). ![]()
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