MGM Mirage officials are investigating the death of a dolphin at an aquatic habitat at The Mirage on the Las Vegas Strip.

Company spokesman Gordon Absher said Monday that animal care officials are trying to determine why the 11-year-old dolphin, named Sage, died Saturday morning.

Absher says 13 dolphins have died at Siegfried & Roy's Secret Garden and Dolphin Habitat since the attraction opened with five dolphins in 1990.

He says that number included five that were stillborn or died shortly after birth.

The dolphin habitat offers tours and hosts birthday parties. It can also be rented as a setting for private events.