8 after he collided with a boat, an accident that ripped a 25-pound (11.3-kg) chunk of flesh from his back and severed his spinal column. Using stainless steel screws and rods, the surgeons realigned the manatee‘s dislocated vertebrae but were unable to repair his spinal cord, leaving him with a paralysed tail. Doctors said at the time they were astonished that the creature had survived at all. The wound, measuring about 24 inches (61 cm) by 14 inches (36 cm) exposed the manatee‘s spinal column and shredded surrounding muscle. The manatee, nicknamed Nash after the man who found him in a Fort Lauderdale canal in mid-July, died late on Monday. Dr. Greg Bossart, a veterinarian at the Miami Seaquarium, where the surgery took place, said the operation had given doctors new insights into the endangered creatures. „We learned we could do an epidural anaesthetic on a manatee. That had never been done before,“ he said. „We learned we could do a very complex procedure to reset a fractured spine.“ A necropsy was scheduled on Wednesday to determine the cause of death. Bossart said the creature probably died from complications of the injuries and surgery. „These animals are amazingly resilient. I know of no other species that could sustain such severe human-related trauma and survive,“ he said. „I would say he died from a propeller injury.“ Manatees are gentle, vegetarian marine mammals that average 10 feet (three metres) in length and 1,000 pounds (454 kg). The species has lived in the warm coastal waters of Florida for at least 45 million years and has no enemies except man. It has hovered on the edge of extinction for years. There are believed to be about 2,300 left. Manatees move slowly and often are found floating just under the water‘s surface. Dozens are killed each year by speeding boats. This year‘s death count stood at 147 at the end of June, one of the worst tolls ever.