The marine mammal habitat-based density models for the Atlantic Ocean and Gulf of Mexico currently featured in MarineCadastre.gov are outdated, and new models will be available online later in 2015. These new models are being developed by Duke University’s Marine Geospatial Ecology Lab in partnership with NASA, the NOAA Cetacean & Sound Mapping project, and the U.S. Navy. The marine mammal data layers currently in MarineCadastre.gov represent habitat-based model estimates of animal density. The model results show estimates of the average number of animals per square kilometer during a given season. Most average estimates per square kilometer feature less than 1.0 animal because marine mammals are highly mobile and often occur in large groups. An average value of 0.5 bottlenose dolphins per square kilometer during the summer could mean a number of things. For example, it could mean that one animal would be present every other day; one group of five animals would be present once in a 10-day period; one group of 50 animals would be present every 100 days; and so forth. For more information on the current models, view the “Uses” or “Publication” options under the “Uses and Metadata” button for the marine mammals data sets.