Fish acting strangely off the Florida Keys heightens the concerns of marine scientists

There's a strange underwater mystery stretching from the Florida Keys to Miami-Dade County. Take a look at that video there. Fish are swimming in circles until they die. Researchers are racing to figure out what's causing this bizarre behavior and how to stop it. Here's CBS News Miami's Elliot Rodriguez. Since last fall, boaters and fishermen in the Florida Keys have seen stingrays swimming upside down, goliath groupers flailing on their sides, and dozens of other species swimming in tortured flailing loops. The strange sightings have mostly occurred in the Florida Keys, but also as far north as Miami. And we happened to see a fish floundering on the flats, and then so we got close to him and we wanted to see if there was a problem, and we could obviously tell that he was in distress. It turned out to be a sawfish, a critically endangered species that might lose four to five mature adults a year. But in just a few months, at least 27 have beached themselves or died after intense episodes of what anglers are calling the spins. We either think of low oxygen conditions in the water or red tide, and so we saw neither. At the water school at Florida Gulf Coast University, Mike Parsons is part of a statewide effort to solve the mystery of spinning fish. And while tests for most toxins have turned up empty, the most promising suspect is found living off of seaweed at the bottom, a tiny critter named Gambierdiscus. This is the highest we've seen of the Gambierdiscus cells in the Keys. We don't know if it's the main cause. The single-celled algae, which can produce various neurotoxins, is showing up in record high levels. But it's just one more stressor on marine life already reeling from pollution over fishing and off-the-charts ocean heat waves brought on by climate change. The hot temperatures in the summer cause some changes that may be led to the fish behavior now, and we just don't really have all the pieces together to try to link one to the other. Greg Firstenworth has taken many of the underwater videos. They really have no idea what is happening. I mean, there is no concrete, conclusive proof of what is happening yet, and that is still to be determined, which is quite terrifying. It is, because if it continues, it's going to be the end of this ecosystem as we know it. That was Elliot Rodriguez reporting there. FWC and the Department of Environmental Protection, they're both testing ocean waters in the Keys, and they've sent at least 50 fish to labs for testing in hopes of finding the cause of this fish kill. We hope they do soon.