On November 26, 2008, the NMFS issued a final rule, effective December 26, 2008, which designated 2,959 square miles (7,664 sq km) as critical habitat for Elkhorn coral. The habitat described is composed of four different areas, which include the coasts surrounding Florida, Puerto Rico, the St. John and St. Thomas area, and St. Croix. These areas were specifically chosen because they contain the surface features which are necessary for the conservation of Elkhorn. In order to increase the amount of successful sexual and asexual reproduction events, the species require hard surfaces within water depths ranging from the mean high water line to about 30 meters.