Are Manatees Actually Totally Fine?
Manatees are listed as 'threatened' under the Endangered Species Act, but a new study says there may be more manatees in Florida now than ever before.
Manatees and their cousins, the dugongs, are a gorgeously strange bunch of mammals. They’re most closely related to elephants—which okay: big, gray, weird nose—but also hyraxes, which are small, fluffy, and fang-toothed. Manatees can weigh more than a small SUV, have basically no natural predators, and survive on a diet of sea-salad that’s so surprisingly tortuous to eat, their jaws have a built-in conveyor belt that just keeps pumping out new teeth so they can replace their chompers as they wear down.
Like I said, weirdos. But extremely lovable weirdos.
So it’s been sad to watch in recent years as news reports hail the impending doom facing the species.
In 2021 and 2022, around 2,000 manatees died in Florida, or around 20% of the state’s population, due to sea grass dying off in the cold winter months. Things were so bad, the state started putting out lettuce for the sea cows to help them survive. And while that was arguably an extra bad stretch, even under normal circumstances, it is still basically accepted that we’re going to lose a ton of manatees each year to highly-preventable causes, such as boat-strikes.
In fact, so many of the marine mammals get carved up by propellers, the Florida Fish and Wildlife Conservation Commission uses the scars they leave behind to identify individual manatees. Which is just… woof.
Add it all up, and you get a ‘threatened’ status on the Endangered Species List here in the U.S., as well as a ‘vulnerable’ status for the whole of the West Indian manatee species (Trichechus manatus), which is found from the U.S. to Brazil, according to the International Union for Conservation of Nature.
In other words, Florida’s manatees are in trouble.
Or are they?
Despite everything I’ve just said, a study published today in the journal PLOS ONE suggests that there may now be more manatees in Florida than ever before.
How could this possibly be? Well, the study’s authors argue that it’s all a matter of shifting baselines. In other words, we don’t really know how common (or not) manatees used to be. Therefore, we aren’t in a good position to say whether the manatees we have are more or less populous than the manatees we had before.
And when I say ‘we’, I mean, like, the earth. Because we’re talking about time scales that stretch far beyond the state of Florida, the United States as a nation, or even human habitation of this continent.
To try to get to the bottom of this, researchers Thomas Pluckhahn (University of South Florida) and David Thulman (George Washington University) scoured archaeological reports from across Florida for evidence of manatees—we’re talking teeth, bone fragments, and the like. Interestingly, this also included manatee bones that were turned into tools or jewelry by ancient peoples, which is a thing.
The researchers also searched through archival records, such as newspaper reports and old explorers journals, for manatee mentions. Though these were tougher to parse, because people used to use all kinds of words for all kinds of things.
In just one example from 1515, one explorer claims to have seen “lobos marinos", or sea wolves, which is the same term another explorer used to describe an animal eaten by Native peoples in southern Florida, as well as the same term used by some other translators to refer to manatees, but also a term used to describe seals. How many of these sources are actually referring to manatees… who the heck can say?
Basically, not all of these records are super reliable, so the researchers threw out anything they couldn’t be sure of.
Anyway, at the end of the day, Pluckhahn and Thulman found surprisingly little evidence of manatees in Florida before modern times.
They also offered five explanations for this lack of data, but the most likely, they say, is that manatees just weren’t really that common in Florida before colonial times. Sure, they probably migrated up from the Caribbean from time to time—as manatees still do today—but in general, the image of Florida as a sea-cow oasis is probably a very recent thing, due at least in part to climate change.
In fact, they say, there’s a real chance that the presence of people may actually be partly why manatees have become as prominent as they are. (For example, manatees love the warm water discharged by our power plants. People also give the animals fresh water off of their docks, and as mentioned before, we feed them, too.)
To be clear, Pluckhahn and Thulman aren’t saying there’s anything wrong with the amount of manatees we have now, or that we should get rid of the sea cows.
“I don’t think they’re doing fine—manatees are clearly suffering—and I hope this research won’t be used to justify lesser protections for them,” says Pluckhahn in an email.
However, when we try to conserve a species, we have to set baselines of what level we’re trying to return to, he says. But this study is an example of how, sometimes, we don’t really understand those baselines.
“Future excavations might reveal additional manatee bones, but it is hard to argue with our sample of over 2 million animal bones (with essentially no manatee),” says Pluckhahn. “Likewise, the scarcity of historical references to manatees in Florida before the 1800s is telling. So the pattern is clear.”
Hold Your Sea Cows
I mean, hold your horses. Sea cows are protected by state and federal law, so you should never attempt to hold them. In fact, Florida FWC also asks that you never chase, poke, prod, stab, snag, hook, hold, grab, pinch, hit, or ride a manatee—a list so specific, you know people have done all of those things.
Honestly, who pinches a manatee?
Anyway, I found the new manatee paper to be fascinating. But I also had questions. So I started reaching out to some manatee scientists, a few of which referred me to Daryl Domning (Howard University), who is an expert in manatee bones.
While Domning seemed impressed with the amount of work the researchers did and the data they were able to collect, he said the conclusions “should be taken with a large shot of salt water.”
“The essence of my reaction is a well-worn proverb,” said Domning in an email. “‘Absence of evidence is NOT evidence of absence!!’”
Basically, Domning says manatee fossils are so rare, they aren’t great indicators of manatee populations.
“These sources show where manatees once were, and where humans once exploited them, but not where the manatees weren’t, or in what numbers. Least of all do they support any suggestions that we now have too many manatees or more than we need, or that conservation measures should be relaxed,” he says.
Pluckhahn seems to agree with that last bit, by the way.
“Manatees and people are now thoroughly entangled in Florida—they are,” says Pluckhahn. “We should protect them because we value them, not because of potentially misguided assumptions about past abundance and what is ‘natural.’”
“I consider manatees almost like a dog that followed us home. We gave the dog a place to stay warm, petted it, and fed it, but then it had a litter of puppies; most of us would say we bear a responsibility there,” he says.