FORT LAUDERDALE (CBSMiami) – South Florida’s cold weather not only has residents and visitors shivering, it has the manatee population seeking warmer water in order to survive. Cold stress is a leading cause of death for the cold-sensitive marine mammals.

Manatees often seek refuge in the warm waters around the power plant at Port Everglades. It’s one of two Broward “hot spots” for manatees; the other is off the South Fork of the New River, south of I-595 and east of SR 441.

Manatees use the Intracoastal Waterway as the main north-south travel corridor to reach these refuges while manatees heading inland will also use the New River and South Fork New River.

Wednesday, state wildlife officials reported Florida just wrapped up the third straight year with high numbers of manatee deaths.

The Florida Fish and Wildlife Conservation Commission said 453 manatee carcasses were documented in state waters in 2011. That’s the second-highest number on record. Biologists reported 766 in 2010 and 429 in 2009.

Biologists say the past three years also had the highest numbers of cold-related manatee deaths. Before 2009, cold stress accounted for an average of 30 manatee deaths a year. That number jumped to 56 in 2009, 282 in 2010 and 112 last year.

Manatees are unable to survive long periods of time in water temperatures below 68 degrees and as temperatures drop, manatees seek refuge in warm springs and around power plants.

Boaters are urged to be extra careful in these areas. The FWC strictly enforces speed limits in manatee protection zones when cold fronts pass through Florida. That’s when manatees are at the greatest risk of being struck by boats.

Agency officials recommend boaters wear polarized sunglasses to help spot the mammals.