Sgt. Pepper, a dolphin at Siegfried & Roy's Secret Garden and Dolphin Habitat, died Wednesday night of complications from a lung infection, five days shy of his second birthday.
Curators at The Mirage facility noted the dolphin's health had been deteriorating since the infection was discovered in December. He was being treated with antibiotics and anti-fungal medicine and, in recent days, was lethargic and had lost his appetite, MGM Mirage spokeswoman Yvette Monet said.
"It is a time of mourning at the habitat for Sgt. Pepper," Monet said. "The mood at the habitat is very somber. This is a very sad loss for us."
Sgt. Pepper was born to two other Mirage dolphins, Dutchess and Lightning, on June 8, 2007. The pair, who live at the habitat and are both in their 30s, are two of five remaining dolphins. They, along with Huf n Puf, Maverick and Bella, who was born last September, are in good health.
The dolphin is the 14th to die at the habitat, a tourist attraction and educational exhibit, since it opened in 1990.
Animal welfare advocates have complained that dolphins aren't suited for such public displays, and that the exhibit's confines are inadequate when compared to the natural habitat of the ocean.
Five of the deaths were of stillborn or newborn calves, Monet said. She said the mortality rate is higher, both in captivity and in the wild, for dolphins at the time of birth.
"They see those patterns all the time," Monet said. "The U.S. Department of Agriculture considers that so significant that they break out numbers whether they died near birth" when they publish mortality information.
Animal welfare advocates contend that intelligent, wide-ranging animals such as dolphins do not fare well in captivity, and that dolphins shouldn't be in captivity at facilities like The Mirage.
All of the dolphins receive routine medical testing by The Mirage's animal care staff, and curators had watched Sgt. Pepper's health closely in recent months. Veterinary experts also were brought in to assist with care.
The average life expectancy of a bottlenose dolphin is roughly 25 years, but they can live to be as old as 50.
The most recent previous death was last July of an 11-year-old dolphin named Sage, who died of unknown causes.
A necropsy will be performed on Sgt. Pepper to determine exact cause of death. Monet said habitat curators believe his illness will not affect the other five dolphins.
She added that respiratory issues are not uncommon for bottlenose dolphins.
The dolphin attraction remains open to the public daily from 11 a.m. to 7 p.m.
Contact reporter Maggie Lillis at firstname.lastname@example.org or 702-383-0279.