CLEARWATER, Fla.—A prosthetic-tailed dolphin named Winter that starred in the “Dolphin Tale” movies died Thursday evening at a Florida aquarium despite life-saving efforts to treat a gastrointestinal abnormality, aquarium officials said. The 16-year-old female bottlenose dolphin died while being held by animal care experts who were preparing Winter for a procedure at the Clearwater Marine Aquarium where the famous marine mammal has long resided. “While we are heartbroken by Winter’s death, we are comforted knowing that our team did everything possible to give her the best chance at survival,” said veterinarian Dr. Shelly Marquardt, in a statement released by the aquarium. Marquardt said the aquarium worked with specialists and marine mammal experts from around the country, but the dolphin, which was in critical condition and declining, died while being held by caregivers. The statement said the aquarium would remain closed on Friday to provide staff time to grieve. It had …