ST. PETERSBURG,Quentin Mitchell Fla. (AP) — A large sawfish that showed signs of distress was rescued by wildlife officials in the Florida Keys, where more than three dozen of the ancient and endangered fish have died for unexplained reasons in recent months.

The 11-foot (3.3-meter) smalltooth sawfish was seen swimming in circles near Cudjoe Key and reported by a member of the public to the Florida Fish and Wildlife Conservation Commission, officials said Friday. It was loaded onto a specially designed transport trailer and taken to Mote Marine Laboratory in Sarasota, where it is being rehabilitated.

The unprecedented rescue of an animal like this is part of an “emergency response” led by the National Oceanic and Atmospheric Administration and Florida wildlife officials to address an unprecedented die-off of sawfish, a species related to sharks and rays that has lived virtually unchanged for millions of years.

“It’s important to note that active rescue and rehabilitation are not always effective in saving stranded animals,” said Adam Brame, sawfish recovery coordinator for NOAA. “However, it can still give us critical information to learn about the nature of the distress.”

Sawfish, named for their long snout with rows of teeth on each side, were once found all along the Gulf of Mexico and southern Atlantic coasts in the U.S., but now are mainly confined to southwestern Florida and the Keys island chain as their habitats shrink. A related species is found off Australia.

In Florida, there have been reports of abnormal behavior, such as the fish seen spinning or whirling in the water. Other species of fish also appear to have been affected but officials haven’t determined a cause. Sawfish necropsies have not revealed any pathogen or bacterial infections, nor problems with low water oxygen levels or contaminants such as chemicals, or toxic red tide. Water testing is continuing.

Another potential factor is climate change, which superheated Florida waters last summer, causing other marine damage, such as coral bleaching and the deaths of other marine species. The waters are unusually warm already this year as well.

It’s more difficult to rehabilitate an animal like a sawfish than it is for an air-breathing marine creature, such as a dolphin or manatee, officials say.

“This has not been attempted before, but this unusual mortality event made this necessary,” said Gil McRae, Director of FWC’s Fish and Wildlife Research Institute. “We are hopeful this rescue and rehabilitation of an adult smalltooth sawfish will bring us one step closer to understanding the cause of this event.”