34 rays die mysteriously at Canadian zoo

Yahoo News 13 May 08;

Authorities said Tuesday they suspect foul play in the recent deaths of dozens of rays at a zoo in western Canada.

Staff at the Calgary Zoo are "puzzled and shocked" by the sudden deaths of its rays, said spokeswoman Laurie Herron.

"It's really devastating for the staff that cared for the animals," she told AFP, calling the deaths "suspicious."

"We cannot find a reasonable explanation for why this happened," she said, adding that "activists' groups or individuals who have become more militant" may be responsible.

The deaths were "certainly not for lack of care," Herron said.

According to a zoo statement, keepers noticed the rays swimming erratically Sunday and observed that they seemed to be in "extreme distress."

Then started dying off. By Monday morning, 34 of the 43 cownose rays were dead.

A preliminary examination found that their gills were very irritated, but otherwise, the animals had seemed in good health.

The zoo's director of conservation Cathy Gaviller said there was no mechanical failure in the tank's life support system, and numerous water tests since the exhibit opened in February were normal.

The zoo sent food and water samples, as well as ray tissue samples to a lab for testing Monday to determine if there were toxins in the water.

"We're still waiting for the latest water chemistry results," Herron said.

The nine surviving rays, meanwhile, were transferred to a separate holding tank and "appear to be doing marginally better today," she said.

Canadian zoo investigates puzzling stingray deaths
Yahoo News 13 May 08;

Officials at the Calgary Zoo remained baffled on Tuesday as they tried to puzzle out just why 34 of their stingrays suddenly died.

The juvenile cownose stingrays, about the size of a dinner plate, were kept in a "petting" tank where visitors were able to touch them, a common feature in a number of North American zoos and aquariums, according to the zoo officials in the Western Canadian city.

On Sunday, within a few hours of opening, the normally voracious fish lost their appetites, became discolored and started dying, with 34 of the 43 rays quickly succumbing to an ailment or cause that has yet to be diagnosed.

"It was a very acute onset of something, a very sudden change," said Cathy Gaviller, director of conservation, research and education for the Calgary Zoo. "It was high mortality in a very short period of time."

The zoo, as yet, has no real idea of what happened to the rays, which are common in the waters off North America's east coast.

Water tests show there were no problems with the tank or its filtration system, though the zoo has also sent off samples for independent testing.

Gaviller said that because of the speed of the deaths, disease or parasites were unlikely causes, but nothing is being ruled out. However results from tissue and toxicology tests won't soon be ready.

"It's unfortunate that we have very few facts," she said. "But the No. 1 likelihood is that something in the water changed suddenly."

She added that there were no signs that a zoo visitor caused the rays' deaths.

The incident is the latest in a number of animal deaths at the zoo that have sparked criticism of the facility.

A hippopotamus being moved to Calgary from Denver, Colorado, died in October. As well, a baby gorilla died in August after other gorilla disrupted the mother's nursing routine.

(Reporting by Scott Haggett; editing by Rob Wilson)

Stingrays probably poisoned, says zoo
Eva Ferguson, Canwest News Service, Canada.com 15 May 08;

CALGARY --The Calgary Zoo has called in the police in the mysterious deaths of 39 cownose rays, now believed to have been poisoned by a visitor.

"This is a huge tank, so something substantial had to have been put in. We don't know if it was a powder or a liquid," said Laurie Herron, a spokeswoman for the zoo.

"But at this point we're thinking it was not accidental."

Tests from an independent local lab released yesterday found the water chemistry of the ray pool was within acceptable ranges. Levels of ammonia, dissolved oxygen, PH, salinity and other natural minerals were measured. Initial tests, however, can't identify possible toxins in the water.

Late Sunday, 26 of the 43 rays died, with other deaths following over the next few days, including one Tuesday evening and another four overnight. The rays were suffering from breathing problems and inflamed gills.

Only four now remain.

Zoo veterinarian Doug Whiteside, who performed the necropsies, said the dead rays had changed from their normal light-grey colour to having splotches of dark grey and yellow. The colour change is normally a reaction to some kind of stress.

The sudden death of so many rays makes it likely a poison was added to the water, said zoo spokeswoman Cathy Gavillier.

"It's disturbing to think of this as a possibility, but we have so far been unable to pinpoint any other cause that would provoke such an acute and severe reaction in the rays," Gavillier said.

Because the rays sickened and died so quickly, disease is an unlikely culprit, she said. Nor was there any mechanical failure in the life-support system.

The ray pool, which allows visitors to reach in and touch them as they swim, was introduced at the zoo in February.