11/26/2014 08:04 EST | Updated 01/26/2015 05:59 EST

Director of humane society sticks up for Winnipeg zoo after seal death

WINNIPEG - The executive director of the Winnipeg Humane Society says it’s unrealistic to expect a zoo or any other agency giving care to animals to be perfect.

Bill McDonald spoke out Wednesday in support of the Assiniboine Park Zoo, where a seal drowned earlier this week after its head became stuck in an underwater drain.

The animal was unable to get free and staff found him dead in his pool Monday morning.

The seal was the second zoo fatality this year that wasn’t the result of natural causes.

A tiger died during a fight with another tiger after a gate was left open that was supposed to separate the two.

McDonald said no agency can plan for the unexpected, particularly if it’s a new facility.

“Sometimes you can’t think of everything and then in the installation, zoo officials can’t guarantee that the work is going to be done 100 per cent according to the architect’s plan," he said. "We’re humans. Sometimes we fail."

McDonald said the humane society also had to make adjustments after moving into its new building in 2007.

Brian Joseph, the facility's director of zoological operations, said the vertical suction drain, about 15 centimetres in diameter, was located on a pool wall with a grate over top. He said the valve has been permanently shut off.

"We don't know exactly what happened. We do know that seals are very investigative. They're always poking around and we suspect he poked around and got stuck," Joseph said Tuesday.

"We're very saddened by his death. We try to keep our animals safe in every way we can but sometimes we're unable to protect them from things that they do."

The male harbour seal, named Caelum, was stranded as a pup on Vancouver Island almost two years ago. Officials with the Vancouver Aquarium determined he was almost completely blind and could not be released into the wild so he was transferred to the Winnipeg zoo in July.