When I heard of biologists using manatees’ many boat scars to tell them apart, I pictured a fast CSI-like computer sorting flippers like fingerprints until, seconds later, MATCH flashed on the screen. Unfortunately, says wildlife biologist Cathy Beck, who runs the program for the U.S. Geological Survey, it’s a lot more slow and still requires a human to make a match. (Cops say the same thing about fingerprint matching, too.)
So the Geological Survey mantains a meticulous database of 2,200 known manatees known as the Manatee Photo Identification System (MIPS). Of those 300 are known to be dead. With a U.S. population roughly estimated at about 3,000 to 4,000, that could be half the population. But the facts about manatees and their populations are so uncertain that Beck doesn’t like to speculate.
Instead, she’s trying to make sure everything in the database is certain. So, she only allows in manatees that have at least two distinguishing features. There has to be pictures of each manatee’s tail, back and each side. In theory that could be done with just four pictures, she says “but that’s never happened.” And then the match has to be verified by two humans. Complicating the process, manatees are constantly aquiring new injuries and changing their appearance. “We need to keep up,” Beck says. “A new injury may obliterate an old feature.”
- At least two distinguishing features
- Clear pictures of the tail, back and each side
- Match verified by two humans
- Wounds have to be healed because they change appearance so much
People may think they’ve seen their favorite manatee, but Beck demands proof: “People are always saying ‘I saw so-and-so,’ but I ask ‘where’s your picture?'”
Complicating matter, she has a number of what she calls “twins,” manatees whose scars are nearly identical. Others, like Ilya, the manatee that recently trekked to Cape Cod and is–we hope–heading on his way down to Florida, ares easy to ID in photos, Beck says. Ilya has a distinctive chunk taken out of his tail and a white scar on his forehead. The head scar is handy for trackers to pick him out when he sticks his head up by docks up and down the East Coast. The fact that he visits docks, however, doesn’t set him apart. Since manatees need to live on the coast, with its mix of salt, brackish and fresh water, they’re naturally around docks. “That’s just what manatees in Florida do,” she says.
Because she only allows complete matches in the system, she has lots of photos that come in that are just sorted by body part, waiting for a match. “We may follow one animal for years and only get its back. We may follow one animal for years and only get its tail,” she says. “And then we find out its the same one.”
Some animals aren’t spotted for a long time. Chessie, the manatee famous for migrating to New England in the 90s, hasn’t been seen since 2001. But, they haven’t found his carcass, either. They once had a manatee that stayed out of pictures for 14 years, then was spotted again. Manatees can live 50 or 60 years, so even the pictures she has of manatees dating back to the ’70s could still be out there.
Some manatees stay out of the database by being clean of scars, while others continually get banged up. Beck has noticed that females are more apt to get entangled in fishing lines around their flippers.
And Beck is hoping to build on the database. The USGS still has thousands of pictures people send in yet to be sorted. And she’d like to track genetics, but already knows the small population is closely related. That will help eventually not only track individuals but help biologists make the population healthy.
Want to See a Manatee in the Wild? Check out this map and list of places.
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