Manatees dying at a record pace in Brevard County, Florida

Many Brevard cases involve younger sea cows
Jim Waymer, Florida Today 12 Dec 09;

A record 105 manatees died in Brevard County this year, almost twice as many as the next highest county and a quarter of the manatees to perish statewide.

Brevard has more habitat; therefore, more manatees tend to live and die here than in any other Florida county.

But biologists are worried about the high numbers that keep dying young. Along the Space Coast, almost half died within a year of birth.

Statewide, 413 sea cows have died this year, putting the species on pace to break the previous record of 417 deaths, set in 2006.

"It's virtually certain that's going to happen," said Pat Rose, executive director of Save the Manatee Club, an advocacy group based in Maitland. "I would love it if that did not happen."

Brevard's total surpassed the previous county record of 87 manatee deaths, also set in 2006, by 20 percent.

Thirteen died here because of cold snaps.

Boats killed six manatees, only 5 percent of the county's overall death toll, and 91 manatees statewide, or 22 percent.

But "perinatal" deaths topped the causes with 48 in Brevard, or 45 percent, and 114 statewide, about 28 percent.

Florida defines perinatal deaths as those that happen before the manatee grows to be 5 feet long -- typically, within a year of birth. The category can include deaths caused by complications with birth and disease.

Boaters against go-slow manatee zones attribute this year's high death toll to a growing manatee population. The record deaths came in the same year the state counted a record 3,802 manatees statewide. The boaters say slow zones do little to protect a species they see thriving.

Manatee conservationists chalk up the statewide deaths from boat strikes and record overall deaths as proof that the species is in peril.

Rose acknowledges that the record perinatal deaths in Brevard may be evidence of robust manatee numbers here.

"But it can't really explain the magnitude of that," he said. "I think it's a really bad year. You don't get these kind of spikes in perinatal deaths without something bad happening."
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But state biologists don't know what that is. They, like Rose, say the high statewide perinatal deaths can't be explained by population growth alone.

The 101 perinatal deaths last year, however, represented an even higher portion of the overall deaths, almost 30 percent. A total of 337 manatees died statewide in 2008.

This year, the biggest portion of deaths deemed perinatal was in animals too decomposed to tell what killed them.

"It's really hard to say something really statistical about those perinatal deaths because they are really based on the size of the manatee, so it has a big mix of causes," said Martine DeWit, associate research scientist at the Fish and Wildlife Research Institute in St. Petersburg.

This year's perinatal deaths in Brevard nearly tripled the previous 20-year average of about 17.

DeWit suspects that the increase may signify more manatees being born this year. But she stops short of declaring a "recovery."

"I wouldn't call it the species recovering. It could be that the population numbers are growing," she said. "That doesn't mean the population is recovering because there are so many threats to manatees."

Those include red tide, declining warm water springs and seagrass disappearance.

"The overall numbers are relatively high this year. And nothing is really jumping out. We didn't have a big red tide die-off this year," DeWit said. "But what was really obvious this year is that we had really strange cold weather peaks."

The state attributes 54 manatee deaths, about 13 percent, to cold stress in 2009, including 13 deaths in Brevard. That was the second highest on record in the county. The highest was 28 cold stress deaths in 1990.