A dolphin jumps out of the water on Feb. 1 at the Dolphin Habitat facility at The Mirage. Photo by Clint Karlsen. Dolphins swim on Feb. 1 at the Dolphin Habitat at The Mirage. Photo by Clint Karlsen. Greg Sabataso, dolphin care supervisor, works with a dolphin on Feb. 1 at The Mirage's Dolphin Habitat. Photo by Clint Karlsen. Dave Blasko Newly hired director of the Dolphin Habitat at The Mirage

Eleven of 16 dolphins housed at The Mirage's Dolphin Habitat have died since the facility opened in 1990, according to federal records and interviews with resort officials.

Although most of the dolphin deaths were attributed to natural causes, they nonetheless caused Mirage officials concern. In 2004, the hotel hired a team of outside experts to conduct an audit of the exhibit.

The audit results were turned over to the U.S. Department of Agriculture, the government entity responsible for ensuring that marine mammals in captivity are properly cared for.

In December 2005, the USDA and The Mirage entered into a settlement agreement in which the hotel agreed to make undisclosed changes as to how it cares for the dolphins at the exhibit.

"The parties recognize that the licensee has voluntarily taken steps to evaluate and to improve its operations," the agreement states.

Despite The Mirage's pro-active efforts, animal welfare advocates were not impressed with the hotel-casino's track record. They contend the number of dolphin deaths proves what they've been saying since the exhibit opened: that dolphins shouldn't be in captivity at facilities like The Mirage.

"It's not simply a case of bad luck that that number has died," said Dena Jones, program manager for the World Society for the Protection of Animals' U.S. office in Framingham, Mass. "Captive dolphins die regularly at relatively young ages. The causes are often not determined. The people (at The Mirage) may be well-meaning and the facility may be well-run, but these type of captive environments can't reproduce conditions in the wild."

The average life expectancy for a bottlenose dolphin is roughly 25 years, but they can live to be as old as 50.

The Review-Journal obtained records from the National Oceanic & Atmospheric Administration that include an inventory of the dolphins at The Mirage and cause of death for those that died. All of The Mirage's dolphins were either obtained from other facilities or bred at the facility.

According to the federal records and also interviews with Mirage officials, a dolphin named Rascal died in 2004 at the age of 3. The cause of death remains a mystery despite a full necropsy of the animal.

Another dolphin born at The Mirage, Pablo, was sent to a facility in Florida for breeding purposes in 2005 and later died from a rare fungus in its lungs. The animal was 10.

A dolphin named Darla died in 1999 of severe chronic pancreatitis at about age 18. A dolphin named Squirt died at the age of 15 due to a respiratory ailment. A dolphin named Picabo died suddenly in 2004 at the age of 11 because of an internal tear in its stomach.

The newly hired director of the Dolphin Habitat, Dave Blasko, said it is unknown what caused the tear. A necropsy found no foreign object in the animal's stomach. A dolphin named Bugsy died in 1997 at the age of 3 from a pulmonary abscess.

One dolphin listed as deceased on the reports was stillborn. Another seemingly healthy calf born at The Mirage died suddenly from pulmonary edema, according to the reports. The baby was 2 weeks old, and Mirage officials suspect the animal aspirated water.

Two dolphins, Sigma and Banjo, died at about age 32 from heart failure. These deaths were described in the federal reports as "age related."

A dolphin named Merlin died of pneumonia. The age of Merlin, like Sigma and Banjo, cannot be determined with certainty because they were originally captured in the wild and housed at other marine mammal display facilities before being brought to The Mirage.

An autopsy estimated Merlin could have been over 40 years old, The Mirage said.

Three other dolphins born at The Mirage, Maverick, Huf-N-Puff and Sage, are alive and well at the exhibit.

A fourth dolphin named Duchess, born about 1975, is also doing well. A fifth dolphin at the exhibit, Lightning, was obtained through the exchange of Pablo with the dolphin facility in Florida, and is healthy.

Mirage officials have said two of the dolphin deaths could be a result of hereditary problems passed down from Merlin to his offspring, each of which was born at the facility, Mirage spokesman Gordon Absher said.

Merlin died of bronchial fungal pneumonia, and respiratory problems were blamed in the deaths of his calves, Squirt and Bugsy.

"From a genetic standpoint, if you were breeding dogs or horses, you wouldn't breed Merlin again," Blasko said. "But all that stuff wasn't apparent."

Regarding the audit, Blasko said The Mirage took the initiative to bring in outside experts in veterinary care, facility design and animal husbandry. "They made all that information available to the USDA, and they made some minor recommendations on some of the practices and changes.

"The USDA looked at it and said, 'We're satisfied with this. We have no complaint with you guys,'" Blasko said.

The Mirage declined a request to release a copy of the audit or specify what changes had been made regarding animal care at The Mirage, but the resort did provide the newspaper with a copy of its settlement agreement with the USDA.

Dolphin experts contacted by the Review-Journal said it is difficult to determine whether there is any sort of pattern to the animal deaths by simply examining marine mammal inventory reports. And, like all animals, some dolphins die before their time, some after the average life expectancy.

Absher and Blasko said The Mirage exhibit, which features 2.5 million gallons of water, has an exemplary reputation for animal care in the marine mammal display industry.

They also said the dolphins in captivity at the facility receive top-notch medical care from an on-site veterinarian and are constantly being monitored and examined for any potential problems. The facility also is committed to breeding the animals.

But animal welfare advocates contend dolphins never were made for such public displays, and that the exhibit's confines simply are not adequate when compared to the natural habitat of the ocean.

"If these dolphins are being well-treated, we're glad to hear it, but there's still no comparison to their real environment," Jones said.

Toni Frohoff, a marine mammal biologist who specializes in dolphin behavior and stress, said dolphins in captivity do not, on average, live longer than dolphins in the wild even though they face no predators and no shortage of food while in captivity.

"Dolphins are free, wide-ranging animals in nature," Frohoff said. "They are one of the few species of mammals that ... in the wild, rarely encounter barriers of any kind. Even what looks like a naturalistic facility to people, with dolphin pens and seawater, serve as a cage to dolphins. There have been several studies showing that intelligent, wide-ranging mammals do not typically fare well in captive environments."