LOS ANGELES (Reuters) - A white tip shark shipped from New York and placed into an outdoor pool for a Kmart commercial in Los Angeles died after showing signs of distress, an official from the animal welfare group that monitored the production said on Thursday.

The American Humane Association (AHA), which certifies film and TV productions with animals, had a representative at the scene of the shoot on March 6 and it says everything possible was done to ensure the 5-foot (1.5 meter) shark's safety.

The shark's death follows longstanding criticism of the use of animals in Hollywood productions. Last year, the horse-racing show "Luck" on HBO was axed after the deaths of three horses used in the drama series.

The animal rights group People for the Ethical Treatment of Animals (PETA), which said it received details on the shark's death from two on-set whistleblowers, criticized the American Humane Association in a letter to the group over the shark's death.

"Sharks are sensitive animals who, in captivity, require a highly specialized and controlled environment," the PETA letter read. "Given the delicate nature of this species, why would the AHA approve the transport and use of this animal?"

The shark was placed into a 60,000 gallon (227 liter) outdoor tank in the Van Nuys suburb of Los Angeles, said Karen Rosa, senior adviser for the film and television unit of the American Humane Association. She added that was a good amount of water for the fish.

"We honestly don't know why the animal died. It was not being mistreated. It was not being harmed," Rosa said.

Early in the day, the shark seemed to be in good condition, but at one point the association representative noticed it showed signs of distress, Rosa said.

"As far as I know, it was immediately insisted upon that the animal receive specialized aquatic veterinarian care," she said.

Oxygen was pumped into the tank and the shark was given a shot of adrenaline to try to stabilize it before it was transferred to an aquatic compound for care, where it died the same day, Rosa said.

The shoot was for a Kmart commercial, but a representative for the retailer could not disclose the concept behind the television spot.

"We take this matter seriously and safety is always our paramount concern," Howard Riefs, a spokesman for Kmart owner Sears Holdings, said in a statement.