More than 100 newborn manatees were found dead in 2008, up from 59 in 2007, according to the Florida Fish and Wildlife Research Institute

The as-yet-unexplained deaths accompany a general rise in all manatee deaths in Florida last year: 337 compared to 317 the year before.

Some of the manatee deaths have obvious causes: 90 adults were killed by speeding boats. But the deaths of the young calves remains a mystery. According to a report from the St. Petersburg Times:

"The culprit may be stress from cold weather, pollution, noise or disease. They might have been poisoned by Red Tide. Sometimes a young manatee may have been orphaned and thus unable to survive alone -- something that leaves no marks on the dead body."

Manatees are an endangered species federally protected under the Endangered Species Act and the Marine Mammal Protection Act, although they are only listed as "threatened" under Florida law. Estimates place the Florida population at around 3,000.

This year's manatee deaths are well below the 417 killed in 2006 and 396 killed in 2005. That's progress, I guess.

Story by John Platt. This article originally appeared in "Plenty" in January 2009.

Copyright EnvironĀ Press 2009