Whatdunnit? Dubuque aquarium probing deaths of most of its stingrays
What killed the stingrays?
That's the question bedeviling officials at the National Mississippi River Museum & Aquarium in Dubuque.
They said eight of the nine rays in the aquarium's touch tank died Dec. 22: five cownose rays, two yellow stingrays and one Atlantic stingray. A single cownose ray survived.
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While veterinarians seek answers, the aquarium overlooking the Mississippi on Dubuque's waterfront announced that until further notice, it is closing the touch pool, part of an exhibit that depicts aquatic life in the river's delta south of New Orleans, where it reaches the Gulf of Mexico.
“The remaining stingray seems to be in good health and is exhibiting normal behaviors. However, they are social animals by nature, so we intend to bring in more animals as soon as possible,” Andrew Allison, vice president of the Smithsonian-affiliated facility, said in an email.
The suspected culprit is a spike in oxygen levels for the 2,500-gallon saltwater tank, detected the night the rays died. Excessive oxygen can cause the rays to suffer lethal embolisms.
Allison said water quality testing and toxicology reports have been completed, but the cause of death will not be confirmed until the aquarium receives necropsy results, which could be weeks away.
Trained aquarists check the tank's water quality system each morning and afternoon, Allison said, and the exhibit has a water-monitoring mechanism, but it failed to send an alert to the staff. Monitoring devices for all the aquarium's exhibits will be reviewed, the news release said.
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Allison said the sympathy shown by fans of the aquarium is appreciated.
“Community support has been amazing. Almost every comment has been positive and understanding. This is incredibly uplifting, especially knowing that these animals are here to raise awareness of the trials and tribulations faced by their wild counterparts,” he said.
Allison added he hopes to have the new stingrays sometime in January. The creatures draw an average of 500 visitors a day, and while they can be touched, the tank is large enough that they can find a place to hide if they don't want the interaction, he said.
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The touch-tank experience won't resume until at least a few weeks after the new occupants arrive so they can get used to the facility, he said.
“The acclimation will go fairly quickly because these animals are already used to people and touching,” he said.
Stingrays in the wild are expected to live up to 12 years.
“Cownose rays are commonly kept in similar aquariums because they are so adaptable and seem to enjoy interacting with people. Many are captive-bred now,” Allison said.
This article originally appeared on Des Moines Register: Touch tank off limits after deaths of Dubuque aquarium's stingrays
