Manatee advocates worry warm waters will leave sea cows vulnerable to boat strikes, cold

Chad Gillis
Fort Myers News-Press

Manatee advocates worry that the fabled sea cow may be in danger this year because waters are running several degrees above average this fall

Cold fronts typically drive water temperatures to 68 degrees or below by mid-November, which triggers a manatee migration to inland waters.

Instead, highs in the 80s have kept water temperatures as high as 74 degrees off Fort Myers Beach, according to weather records. 

So instead of clustering up in warm-water refuges like the water discharge at the Florida Power & Light plant along the Orange River just outside Fort Myers, manatees are still swimming in bays and along the coast. 

"There are transitional times where manatees are going to be rather than where they would be if it were colder," said Pat Rose, with Save the Manatee Club. "They're still dispersed a little bit and they're not making that huge transition." 

A manatee mating herd is seen off of Bonita Beach near the north end on Wednesday, June 29, 2022. The sea cows can be seen off of area beaches and in the estuaries during this time of year.

That could put manatees in areas like Estero Bay in danger, advocates say, as most of the bay opens up to 25 mile per hour boat traffic on Nov. 15. 

There, instead of being confined to relatively narrow channels, like they are during the summer, boaters can roam most of the open bay on plane. 

A deadly year for manatees? 

Overall, 2022 is turning out to be a deadly year for manatees. 

The Florida Fish and Wildlife Conservation Commission is in charge of protecting species like manatees, and agency records say this is already the third deadliest year on record in Florida waters. 

Through Nov. 25, 749 manatees deaths have been documented this year in the Sunshine State. Last year a record 1,027 manatee deaths were tallied, according to FWC records. 

Most of those deaths were due to a starvation event in the Indian River Lagoon, which claimed hundreds of sea cows over the past two years. 

Deaths from watercraft strikes are on the low side: 71. The record for boat kills is 124, which was set in 2018. 

The second deadliest year on record was 764 documented deaths in 2018, according to FWC records. 

Red tide claimed hundreds of manatees in Southwest Florida waters that summer. 

"That terrible 2018 year," Rose said. "We had so much red tide mortality and this is competing with it. It's nip-and-tuck whether it's going to be that high. All the circumstances are there that could lead to that." 

The short-term future will include water temperatures dropping below the 68-degree mark, which is when manatees start to suffer from cold stress. 

"It's not an absolute but it's the one we use because below that they are looking for warmer waters," Rose said. "And 74 (degrees) is about what our springs areas, so that's certainly safe for them. If it is that warm there is a greater likelihood they'll be away from the warm-water refuges." 

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Jacki Lopez, with the Center for Biological Diversity, said she's concerned that warmer waters will keep manatees in coastal waters and that a cold front could come and leave them exposed. 

"They come inland when the waters get cold," Lopez said. “What if manatees are staying out (along the coast) a little bit later because the water is warmer and then we get a cold snap.”

Lopez said changing climate conditions will likely cause waters to be warmer later in the year in the future, but that cold snaps are expected to be less frequent but more intense.  

"How can we adapt our management of waters to reflect some of these changes," Lopez said. "What should we be looking at to keep manatees safe? Maybe it's not arbitrarily picking a date but some monitoring based on manatees using water." 

Rose said manatees face many challenges in Southwest Florida, from red tide to hurricane debris and chemicals and pollution washing off the landscape in the wake of Hurricane Ian. 

"We've still got so much debris in the water and the red tide," Rose said. 

Connect with this reporter: @ChadEugene on Twitter.