The Calgary Zoo admits they knew months ago what caused the death of 41 cownose rays.
Dr. Clement Lanthier, the president and CEO of the Zoo, says human error and faulty equipment is to blame. "There were four pumps, including the life-support system, and occasionally one was failing and in the past that happened for many weeks," says Lanthier.
Lanthier says he knew as early as November that oxygen levels were too low for the animals to survive. "We believe the dissolved oxygen was too low. The life-support system was not designed to provide enough dissolved oxygen," said Lanthier.
Up to this point, officials with the Zoo said there were a number of potential causes for the death. "Several possibilities remain including unknown toxins or possible deficiency of dissolved oxyben in the water but a conclusive cause may never be known," the Zoo stated in a December press release.
Lanthier also admitted on Tuesday that the Zoo's lack of expertise in dealing with aquatic animals was also an issue.
The Zoo's admission of error is fueling criticism from animal advocates. "They put these animal's lives at risk. They played Russian roulette with the welfare of these animals and unfortunately they all died," says RJ Dailout, a spokesperson for Zoocheck Canada.
A new ray exhibit is already open and the tank's life-support system has been upgraded.