Population Assessment Finds Too Many Manatees Suffer Death-by-Boat-Strike

The U.S. Fish and Wildlife Service has announced new stock assessments for manatees that puts the population of Florida manatees at about 3,800 and a Puerto Rico population at 72. The stock assessment reports resulted from a settlement of a lawsuit brought by the Center for Biological Diversity that sought updated assessments, since the Service had flouted its duty under the Marine Mammal Protection Act to publish yearly reports for more than a decade.

Manatees are large marine mammals that live in estuaries, bays, and rivers. They require warm waters and tend to gather around warm springs or other sources of warm water. They grow to be about nine feet long and weigh about 1,000 pounds. They are slow-moving and gentle and graze for food along the sea floor and surface. Manatees are herbivores, eating aquatic plants such as sea grasses.

According to the Service's stock assessment report on the Florida manatee population, each year about 87 manatees are killed by humans in the state. This is more than seven times number of manatees that the Service estimates can be killed without impairing the species' recovery. Boats are the primary threat to manatees, which are frequently struck and killed or seriously injured by speeding vessels. Almost 90 percent of the manatees killed by humans were a result of such boat strikes. Manatees are also threatened by water diversion structures, such as dams, and entanglement in marine debris, including derelict fishing gear.

"The Fish and Wildlife Service's data shows us that boats are carelessly killing manatees," said Miyoko Sakashita, an attorney with the Center for Biological Diversity. "It is clear that there is too little being done to protect these endangered manatees in Florida."

While the threats to manatees are undisputed, the stock assessment reports are somewhat controversial. The Fish and Wildlife Service rejected the advice of the Atlantic Scientific Review Group, which reviews the manatee reports, that there should have been separate stock assessments for different Florida manatee subpopulations. Florida manatees are managed as four distinct regional management units: the Atlantic Coast, Florida Keys, lower St. Johns River, and upper St. Johns River. According to the Scientific Review Group, manatees in each of the regions are exposed to different threats, and some have different population trends; for example, the Florida Keys unit is declining, while other populations are stable or increasing.

"The one thing that everyone should be able to agree upon is that manatees in Florida and Puerto Rico need additional protections from boat collisions to provide the best possible conditions for the conservation and recovery of manatees," said Sakashita.

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 September 10, 2009.