With two months left in 2013, manatee deaths have already broken the record set three years ago. Boaters are not to blame — in fact, the number of manatee deaths from being hit by boats are down.
As of this week, the number of manatees killed in 2013 has hit 769, according to records kept by the Florida Fish and Wildlife Research Institute in St. Petersburg.
That means more than 15 percent of the estimated population of about 5,000 has already been killed, and as the year goes on the total will continue to climb.
"I'm sure we're going to wind up well over 800," said Pat Rose of the Save the Manatee Club.
The old record, set in 2010, resulted from a lengthy cold snap that killed hundreds of manatees, pushing the year's total to 766.
This time the big die-off has been blamed on a massive Red Tide algae bloom in southwest Florida — which caused 276 deaths total — and a mysterious ailment that has been killing manatees in the Indian River Lagoon on the state's east coast — 116 as of last week, according to Kevin Baxter of the state's wildlife biology lab.
The investigation into what has been killing manatees in the Indian River Lagoon is continuing, Baxter said.
This summer, a government research chemist announced he had isolated what he called "a suite of toxins" on seaweed eaten by the manatees that died in the Indian River Lagoon. Some of the toxins appeared to be previously unidentified by science.
The manatees filled their bellies with the reddish seaweed called Gracilaria because their normal food, sea grass, had been wiped out by a series of huge algae blooms fueled by nutrient pollution in the lagoon. The algae blooms left empty more than 47,000 acres of its sea grass beds, which one scientist compared to losing an entire rainforest in one fell swoop.
Initially, scientists thought fertilizer was the source of the pollution, but tests by Brian Lapointe from Harbor Branch Oceanographic Institute found that the culprit is actually sewage.
While that narrowed down the cause of death for the manatees, it still did not explain the widespread deaths of the dolphins and pelicans.
Meanwhile the number of manatees killed by boats appears to have dropped this year. This time last year 72 manatees had been clobbered by boaters, Baxter said, and the five-year average for the end of October is 75, he said.
But so far this year boaters have killed only 62 manatees.
That may be partly because, with all the die-offs, "there are fewer manatees to kill," Rose said. The counties that tend to lead the state in boating deaths, Lee and Brevard, have also been the scene of the Red Tide and Indian River Lagoon die-offs.
Rose also credited the speed zones put in place by the state wildlife commission and enforced by state and federal officers for cutting the number of boat-related manatee deaths.
Last year the libertarian Pacific Legal Foundation petitioned the U.S. Fish and Wildlife Service to take manatees off the list of endangered species and instead list them as threatened.
Federal officials said then that they expected to begin the process of changing manatees' classification sometime this year. However, the federal budget sequestration "has adversely affected our efforts to track Florida manatees," hurting the data-gathering necessary for taking that step, said Fish and Wildlife Service spokesman Tom MacKenzie. As a result, any decision has been pushed back until next year, he said.
"We are concerned about the high mortality," MacKenzie said.
Rose contended that the record-breaking death toll this year, as well as continuing concerns about the manatees' loss of habitat in the state's declining springs, should be reason enough to end that effort.
Craig Pittman can be reached at firstname.lastname@example.org