Boats are the primary threat to manatees, and about 90 percent of the manatees killed by humans were a result of boat strikes, according to the Center for Biological Diversity.

The U.S. Fish and Wildlife Service puts the number of Florida manatees at about 3,800 and the Puerto Rico population at 72, according to a stock assessment report.

The report on the Florida manatee population shows that each year about 87 manatees are killed by humans in the state. This is more than seven times the number of manatees that the service estimates can be killed without impairing the species' recovery, according to the center

Stock assessments are required under the Marine Mammal Protection Act and are meant to be used as the basis for management decisions such as those permitting the killing or harassment of the animals by commercial fisheries, oil and gas exploration, boating and shipping, and military exercises.

The Fish and Wildlife Service is accepting comments on the draft stock assessment reports until Sept. 10.

For more on the report, click here.