Scientists race to save Florida's spinning, dying fish

For the first time in U.S history, scientists launched an emergency effort this week to rescue critically endangered smalltooth sawfish, which are succumbing rapidly to the mysterious fish ailment ravaging the Florida Keys.

As of early April, 30 sawfish have died, all of them older juveniles or adults, ranging from seven to 14 feet in length. There are likely only about 650 breeding females living in Florida, one of only two remaining wild populations left due to overfishing and loss of habitat throughout the Atlantic.

“This level of mortality on an endangered species is unprecedented. And therefore, to some degree, this is an unprecedented response,” says Adam Brame, sawfish recovery coordinator for NOAA Fisheries, one of the government agencies working with a network of private aquariums and nonprofits to capture the fish and bring them into captivity.

A type of ray, the smalltooth sawfish has a flattened body with a large tooth-studded saw, or rostrum. They slash their saw side to side to stir up critters in the seafloor and stun fish, and use it to defend themselves against predators such as sharks. 

“It looks like a hedge trimmer on the front, a stingray in the middle and a shark on the back end,” says Brame. “If you put those three things together and have a little

cauldron, then poof, out pops a sawfish.”

The smalltooth sawfish, which can live 30 years, is also notable for being the first marine fish to receive federal protection under the Endangered Species Act, in 2003. Conservation efforts had been slowly building the sawfish population back up—until now.

“The entire U.S. population depends on Florida, which is a lifeboat population,” says Yannis Papastamatiou, a marine biologist and shark expert at Florida International University who is not involved in the rescue initiative. (Learn more about marine wildlife under threat.)

That’s why, he says, such an urgent response is so crucial. “To suddenly start losing all of these animals … could be potentially catastrophic and could potentially turn back decades of conservation.” 

Since November 2023, a total of 57 fish species in Florida have displayed the spinning behavior, caused by an unknown culprit that is under investigation.

How to rescue a sawfish

To rescue the rays, the recovery team is monitoring a hotline that the public can call to report sightings of sick or distressed sawfish, which live in shallow coastal waters.

If one is reported, the team will then travel by boat to find the sawfish and determine if it’s possible to capture. Catching sawfish is tricky; unlike sea turtles or marine mammals that breathe air, sawfish need to stay underwater.

Once they locate the sawfish, the team will take measurements and blood samples, as well as tag the animal so if it does live, it could be found later, says Brame.

If it's possible to remove the animal, experts will hoist the sawfish onto the boat or a small, water-filled vessel towed behind the boat. Next, they'll take the sawfish to a local holding tank in the Florida Keys to monitor its condition, says Brame. 

If the fish seems stable, it can be transported to one of three partner facilities, including Mote Marine Laboratory and Aquarium, via a specialized truck that's essentially a 30,000-gallon moving aquarium. 

Once at the facility, staff will observe and rehabilitate the animal until it recovers. Ideally, once the abnormal event has resolved, the fish will be safely released back to the wild. (Read about the search for the world's last remaining sawfish.)

No one knows what's causing fish to spin in circles and die, though scientists have ruled out high water temperatures, low oxygen, parasites, or a red tide. Scientists have, however, found elevated levels of certain toxins produced by a type of microscopic algae.

Brame says the sawfish rescue was motivated in part by the uncertainty of what’s causing the deaths, and when it will end.

“Sitting back waiting for an endangered species to die is just irresponsible,” he says.

“We’re not sure how it's going to turn out, obviously, this has never been done. But as long as we are making positive strides, then the effort will continue.”