Protection of the natural environment is an integral part of U.S. Navy activities. A key focus of the Navy’s environmental stewardship at sea is the protection of marine species, including marine mammals. In partnership with the National Marine Fisheries Service (NFMS), the Navy develops and implements appropriate science-based protective measures to protect marine mammals during Navy operations at sea. Protective measures include posting highly trained lookouts prior to and during an exercise; listening for marine mammals with passive hydrophones; reducing sonar levels or ceasing use of sonar altogether if marine mammals are detected within certain distances of the vessel’s sonar dome, and conducting aerial searches for marine mammals in the area before, during and after sonar operations.