Entire enclosure of animals dies overnight in puzzling incident at Florida zoo

Zoo says it will bring in outside experts to investigate cause of sudden deaths of 12 stingrays

File image: A cownose ray swims at the Aquarium of the Pacific in Long Beach, California, on 26 April 2012 (AFP via Getty Images)

Almost a week after 12 stingrays died at ZooTampa at Lowry Park in Florida, zookeepers are still scratching their heads over the cause of their deaths.

Conditions in the tanks were “optimal” at the time, according to zoo staff, and subsequent tests have shown no anomaly or mechanical problem.

The zoo staff had noticed that the stingrays were acting strangely soon after the ZooTampa opened on Thursday 27 May, reported Tampa Bay Times. But it was already too late as veterinary teams rushed to check on them, as all 12 died within an hour.

The 16,000-gallon saltwater touch tank, known as Stingray Bay, housed seven cownose, four southern and one Atlantic stingray, all of whom died suddenly. The three species belong to the same group as sharks with cownose rays being listed as vulnerable on the red list of the International Union for Conservation of Nature (IUCN).

A probe into the equipment and water quality led to no conclusive finding on the death of the fish, Dr Cynthia Stringfield, senior vice president of animal health, conservation and education, was quoted as saying.

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Further, the internal investigation has revealed no suggestion of foul play, she said. So far law enforcement agencies are not involved in the investigation.

“We are emotionally exhausted,” Dr Stringfield said. “(Thursday) was just a horrible day. It’s like a day out of your nightmares, pretty much... We’re really focused on trying to get to the bottom of what happened.”

In a statement, the zoo said it was investigating “every possibility” to uncover the cause of death including “toxicology reports” but it may take weeks for all the results to come in.

Dr Stringfield said that the zoo would also be bringing in outside experts to look into the matter.

The zoo authorities first shared the news of the mysterious deaths on its Facebook page, with the post receiving thousands of interactions from people sharing their condolences, or memories from the time they had visited the Stingray Bay.

“We’re just floored by the outpouring of sympathy and support from the community. It’s been amazing and it’s been amazing to see how impactful those animals were for so many people,” Dr Stingfield had told ABC News.