More than 200 manatees have died in Florida's waterways since January from an algae bloom called red tide, just as wildlife officials try to remove the marine mammal from the endangered species list.

It used to be boat propellers that were the biggest killer of manatees, but red tide has been especially bad this year.

Florida Fish and Wildlife officer Steve Rice routinely scours the Caloosahatchee River in southwest Florida for dead manatees. He has found more than 20 in the past few weeks.

"It's part of the job, but it's not something we like doing. It's pretty terrible, and we have to come out and dedicate a day of our job to searching for sick or injured animals," Rice says.

Rice says most of the deceased manatees are being reported by people kayaking in the river. Tim Martell, who leads manatee kayak tours, says the past few months have been devastating.

"I think that it's terrible. Red tide is something that is not good for the ecosystem overall and obviously not for these animals that are dying from it," Martell says.

It's impossible to contain or control red tide. The blooms occur naturally almost every year along Florida's Gulf Coast. The algae produce toxins that are absorbed by the sea grass, which manatees eat.

No one knows why the outbreak is so severe this year. Mike Parsons, who teaches marine science at Florida Gulf Coast University, says bad luck is partly why so many manatees have died.

"The bloom is fairly persistent and fairly large, but it's not the worst of blooms. But I think just the way the winds are blowing — it's getting on sea grass beds, it hasn't been so cold that the manatees are going upriver, things like that, so they are still out feeding," says Parsons. "I think it's just a lot of bad luck."

The manatee population has rebounded in the past few years. Federal officials believe there are now about 5,000. There had even been debate about downgrading the species from endangered status to threatened. The U.S. Fish and Wildlife Service says this year's rash of deaths may complicate that.

Rice says in the meantime he is also keeping his eyes peeled for manatees that are sick but not dead yet. Manatees in distress from red tide struggle to come to the surface to breathe, he says.

"It actually causes seizures," Rice says. "When we get in the water to try and rescue them, we can actually feel them seizing as we hold their head up to help them breathe."

If manatees are rescued in time, they have a very good chance of recovery at several marine rehabilitation centers around the state. But Rice says that does little to help the record number of manatees that have already died this year in Florida.