Miami, Florida (CNN) -- Five months after the Deepwater Horizon explosion unleashed a torrent of oil into the Gulf of Mexico, a male dolphin washed up on Louisiana's Gulf Coast just barely alive.
"Other dead ones [dolphins] had exterior oiling on them," recalls Michele Kelley of the Audubon Nature Institute in New Orleans. "He was the first live oiled marine mammal."
Oil covered the dolphin's body, but little was found in his blowhole or mouth -- a good sign. Rescuers noticed that the animal appeared to be underweight for his size and put his age at about 2 years old.
The rescuers also saw injuries and believe he was beaten by another dolphin.
"For an animal as young as he is, he has a stat of about a 5% chance of survival," said Kelley, who oversees the rescue of stranded animals in Louisiana for the Audubon Nature Institute. "Him, I would have given him maybe 2% max. He had a lot of issues, oil was his final issue."
The rescue team photographed him and recorded him under the name LA-405. He was later given the nickname "Louie."
The rescue team took Louie to the Audubon Aquatic Center in New Orleans, cleaned him off, and began teaching him how to swim again.
A staff member had to be in the water with him around the clock to hold Louie above the waterline so he could breathe. Otherwise, he would sink.
It took over two and half weeks until the little dolphin showed signs of improvement. Louie started eating fish on his own and started learning how to swim again by moving his tail up and down.
That was the beginning of an intense rehabilitation process. In the end it would take 700 hours of care over five months before Louie would be declared healthy.
That was a bittersweet time for the Audubon Aquatic Center staff.
"You cry. You shed tears," Kelley says, "You put five months into this animal, his rehab and seeing him everyday and taking care of him. Then it's time for him to go and we know that it's the best thing for him."
Despite his progress, it is too risky to release Louie into the wild because of his young age. So this week, with the help of the U.S. Coast Guard, Louie was transported the Dolphin Research Center in the Florida Keys, a nonprofit organization that cares for rescued dolphins.
"In dolphin maturity he would still be dependent on his mom and that whole structure of a maturity pod to learn foraging, to learn survival techniques, avoiding predators, things like that," said Mary Stella, a spokeswoman for Dolphin Research Center.
In Louisiana, 62 dolphins have been collected since the oil spill, and all but two were found dead, according to Kelley. One of the two rescued died during rehabilitation. This left Louie as Louisiana's sole survivor, and the only rehabilitated dolphin to survive the worst oil spill in U.S. history.
Having just arrived at his new home, Louie will eventually be integrated into a group of other dolphins at the facility. He will also have to get used to his name, which he received upon arrival in the Florida Keys.
"Part of the reason we named him Louie is to immediately connect him to his Louisiana roots because here you have a little guy who has a real survivor story to tell," Stella says. "He serves as a reminder of the importance of protecting these animals out in the wild and protecting the environment."