Red tide has been killing ten or more manatees a day. On Friday the number reached 149 so far this year. By the end of the weekend, that number could pass the record set in 1996 at 151 deaths.
Biologists say it's unclear if the algae bloom will let up any time soon.
Nearly a dozen manatees have been rescued and are being treated at the Lowry Park Zoo in Tampa.
Red tide turns the water into a rust color, releasing large amounts of toxins. The current bloom affects 70 miles of the southwest Florida coast, from Sarasota through the middle of Lee County.