ST. PETERSBURG — Red Tide algae blooms and speeding boaters helped push manatee deaths in Florida to 538 in 2017, the third highest total on record, according to figures compiled by the state’s Fish and Wildlife Research Institute.
Red Tide, a type of toxic algae that has repeatedly bloomed off Florida’s coast since the days of the Spanish conquistadors, "did play a significant role in manatee mortality last year," institute spokeswoman Michelle Kerr said Monday.
Red Tide produces toxins that can paralyze manatees so they drown. The southwest Florida area from Pinellas down through Collier counties experienced a persistent Red Tide bloom from October 2016 through spring 2017.
The state "documented 63 Red Tide-related carcasses during this event in 2017," Kerr said.
Scientists believe Red Tide algae blooms are not caused by humans — they can develop up to 40 miles offshore. But scientists say that once the blooms move closer to shore, expanding into estuaries and bays, their continued existence can be fueled by nutrient-laden runoff from human overuse of fertilizer and from leaking sewage lines and septic tanks.
Speeding boats killed 106 manatees last year, according to the FWRI figures. That’s the same number of manatees killed by boats in 2016 — the first year on record in which the number hit triple digits. Eight were killed by boats in Pinellas County, five in Hillsborough, one in Hernando and none in Pasco County.
The high number of boat-related deaths "is not a surprise," said Patrick Rose, executive director of the Save the Manatee Club. He noted how many people bought new boats in Florida last year and pointed out that the low price of gas makes it more economical to take those boats out for a run. About 931,450 boats are registered to owners in Florida.
Rose said the number of manatee deaths would have been even higher if not for the team of rescuers and rehabilitation experts who saved scores of injured manatees and enabled them to survive their wounds.
And he predicted that poisoning by Red Tide is likely to be a recurring problem, noting that the bloom has been producing fish kills in that same area in recent months.
Every manatee found dead in Florida is brought to the state’s wildlife research laboratory in St. Petersburg for an examination called a necropsy, which is designed to determine the cause of death.
The highest manatee mortality number for one year is 830, a record set in 2013 amid a deadly cold snap and a wave of poisonings by Red Tide, as well as a mysterious ailment in manatees found in the Indian River Lagoon that’s still under investigation. In 2010, 766 manatees were killed, the second worst year on record.
Manatees had been listed as endangered ever since the first endangered species list was published in 1967, but last year the U.S. Fish and Wildlife Service changed their classification to "threatened," a lower status, despite the objections of scientists who reviewed the agency proposal.
Instead of science, one biologist said, the agency’s decision "seems to be based on hope."
Nearly 87,000 comments and petition signatures opposing the change were submitted during the 90-day public comment process. Only 72 people said they were in favor of reclassifying manatees.
Contact Craig Pittman at [email protected] Follow @craigtimes.