Journey North Manatees

When the entire population of a species is so small, it is placed at serious risk if a widespread disease comes along. Just a few years ago the manatees faced such a risk when they were exposed to red tide. In 1996 alone, red tide alone killed 151 manatees, and that didn't even count all the manatees that died from other causes that year!

Already this year too, scientists from the Florida Marine Research Institute suspect that 27 manatee carcasses brought in from four southwest counties between March 15 and April 16 died as a result of exposure to red tide. Samples collected during necropsy were sent for a toxicological analysis that shows whether the red tide toxin is present in an animalís urine, stomach, and liver.

A federally appointed advisory panel, The Working Group for Unusual Marine Mammal Mortality Events (WGUMMME), has declared this an unusual mortality event.

3) How fast is the rate of reproduction in this species?

Manatees have a very slow reproduction rate. According to Nancy Sadusky from Save The Manatee Club, scientists believe females do not become sexually mature until five years of age. Males are mature at approximately nine years of age. Once they are mature, manatees usually bear one calf -- twins are rare. Intervals between births range from two to five years, and the gestation period is approximately 13 months.

The number of manatees that die each year in Florida has generally increased over the years. When scientists started counting in 1975, they recorded 29 manatee deaths that year, 6 of which were from boating causes. Last year, the 2001 count was 325 manatee deaths, with 81 coming from boating causes.

Boat Registration Graph
click to enlarge

Credit: USGS-Sirenia

Boating related deaths have followed right along with the increasing number of boats in Florida.

5) Do non-fatal injuries affect Manatee reproduction?

In addition to the growing number a manatees killed by boats each year, many more are hit by boats and survive, but often with horrific injuries. Scientists are just beginning to study what effect these injuries may have on the overall health of the Manatee population? One of the topics they will study is the question of whether injured manatees may not be reproducing successfully?

6) Are other species protected more than Manatees? Why?

Several manatee scientists have noted that manatees do not receive the same level of protections as other species, especially when the data shows that so many deaths are being caused by a single cause-- boating.

In a March 1, 2002 article in the Palm Beach Post, Greg Bossart, director of marine mammal research and conservation at Harbor Branch Oceanographic Institution, said that this level of human-caused death would not be tolerated for other species. "'If we were doing these same things to any dolphin species, I guarantee you there would be a public and government outcry from here to Washington,' Bossart said. 'Animals that have more appeal to our emotional needs or spiritual needs or whatever get more attention. They (manatees) didn't get a TV series.'"

Credit: FWC

What if Manatees had gotten their own TV show, like Flipper?

One Out of Every Four!
In the same article, Save the Manatee Club biologist Patti Thompson said that people should be shocked. Approximately 25% of manatee deaths, that's one out of every four, are killed by boating, which she described as "something that was preventable just by being more careful." She commented that if there was a single thing causing 25% of human deaths, "don't you think we'd be pretty worried about that?"