Gladys Porter Zoo officials are “befuddled” as to what caused the death of five stingrays in its aquatics exhibit.
The five stingrays were found dead Monday morning. They were last seen alive Sunday.
The loss of the stingrays comes about a year after 18 stingrays were found dead Jan. 14, 2022, residing at the Landing at the Russell Aquatic Ecology Center, following equipment malfunction. These stingrays were found at the bottom of the tank.
In the latest deaths, officials said all life support systems were fully operational and that it was confirmed by an externally monitored alarm system that their pump and filtration system had operated properly throughout the night, zoo officials said in a news release.
“The appearance of the stingrays was very similar to last year, it just looked like they were sleeping,” said Colette Adams, deputy director at Gladys Porter Zoo, Tuesday.
Although water chemistries were performed, the results did not provide any information that would help determined what caused the stingrays to die.
The zoo’s veterinary staff performed necropsies on the stingrays and found them in good physical condition. “They were not too thin, not too fat, no internal or external sign of disease,” Adams said. “There was food in their stomachs; they had eaten the day before. They went from healthy on Sunday, apparent healthy on Sunday to deceased by Monday morning.”
Adams said zoo officials have checked off what needed to be checked off and all was found functionally normal or in normal limits.
“We are befuddled at present,” Adams said.
The next step officials will take is to send tissue samples taken from the stingrays to a veterinary diagnostic laboratory to see if there is something that cannot be seen in a necropsy.
“We will also take a look at the water sample we took from the tank to see if there were any toxins introduced into the water that normally our testing can’t pick up, and we are also going to send off a food sample,” Adams said. “Currently we are not feeding any of the batch of shrimp that those animals were fed from on Sunday just in case there was some toxin in them. That’s all left for us to do at this point.”
“The indication would be that there was an event, an episode, something that they were all definitely exposed to,” Adams added.
Following the deaths of the stingrays in January 2022, the zoo has evaluated and upgraded all of the electrical systems in the Russell Aquatic Ecology Center and has “engaged the services of outside technicians to install an alarm system to relay pump failure messages, via email and text messages, to all aquarium and night keeper staff. The system, which is also monitored externally by the installing controls contractor, has worked flawlessly,” the zoo said in a news release .
The release concluded stating “The Gladys Porter Zoo is deeply committed to every animal in our care, and if there is something we need to do differently, we will do it. Using both internal and external expertise will help ensure that there are no unnecessary future losses.”
