Introduction
In Fall 2002, a female bottlenose dolphin (Tursiops truncatus) "Fuji" kept in Okinawa Churaumi Aquarium lost 75% part of her flukes because of an unknown disease. Would it be possible to make the world's first artificial fin? Would this fin allow her to swim and jump again like normal dolphins? For scientific research, we started this experimental study on artificial tail flukes in cooperation with Bridgestone Co.

About "Fuji"
Fuji was caught in Kawana, Itoh, Shizuoka prefecture and transported by air to Ocean Expo Park, Okinawa in November 1976.
Her estimated age is 36, approximately 271 cm in length and weighs 216 kg as of April 20, 2005. She is a mother of three children: Ryu (male, 26 years old), Konny (female, 15years old), and Chao (male, 9 years old). Ryu died of disease 29 May 2005. Ryu was 27years old and has been the oldest bottlenose dolphin born in captivity in Japan.

The unknown disease on her flukes
Fuji has suffered from the unknown disease since October 2002. She had symptoms such as loss of appetite, discoloration and necrosis in distal parts of flukes. The blood analysis and biochemical examination revealed she had a complex of infection and circular insufficiency. During treatment with antibiotics and transfusion for 60 days, we excised the diseased parts by electronic surgical knife on October 25 and on November 7. She thoroughly recovered from the disease, although she lost 75% of her flukes.

The first step of the project
This projected first started when our veterinarian consulted for assistance to Bridgestone Co., Japan's largest tire maker on November 27, 2002. One week after this contact, Bridgestone Co. agreed to cooperate in the project. To compensate her lost tail, we officially started to develop artificial tail flukes in May 2003.

The goal of this project was to give scientific answers the following questions:
・Does the artificial fin function as parts of flukes?
・Can Fuji fully recover her normal swimming behavior with the artificial fin?
・Can Fuji fully recover her social interaction with other dolphins with the artificial fin?

We started this project not from the compassion for Fuji only, but for a scientific experiment. Fuji did not have any problem living in the aquarium. It was reported that wild cetaceans without tail flukes appeared.


How to make an artificial fin
The first fluke cast was made of silicon on July 5, 2003. We developed the first prototype (48cm wide, 30cm long, 2000g), but when tested on Fuji, it did not work well because of the attachment problems. The design of attaching belts caused scratches on her flukes. After reconsideration, we decided that we needed a more accurate mold of Fuji's tail. Mr. Kazuhiko Yakushiji, a famous acrylic sculptor kindly joined this project.
At the beginning of March 2004, the second model (70cm wide, 25cm long, 2200g) was made. We also found a better way of attachment by a cowling made of carbon fiber reinforced plastic. The prosthetic tail is kept together by bolts.
On June 12, the second model with cowling (70cm wide, 25cm long, 2200g) was tested on Fuji.
This experiment was successful. When wearing this model, the dolphin could swim speedily and even jump into the air as she had done before.

　At this stage, the artificial fin was mechanically strong enough for swimming but not enough to sustain physical momentum of jumping. We are still trying to improve the material for the reinforcing board and silicon rubber strength.

Institute of Cetacean Research and our aquarium are collaborating to analyze the swimming speed of the dolphin and demonstrate a significant benefit of such artificial fins.

Training of Fuji
Rehabilitation training (1st stage)
In nature, the dolphins don't like to be attached a foreign object on their body. Fuji initially rejected the artificial tail. Therefore, we phased attachment training for Fuji.
For dolphins' health control, it is very important to accustom them to medical examination. They need to allow the trainers to insert a thermometer into their anus and they need to lift their flukes out of water for taking blood samples. These trainings make it easy to check dolphins'health conditions. The rehabilitation training of Fuji was similar to these trainings.
1) First, we taught Fuji to show her flukes at the trainer's sign and let the trainer touch the flukes.
2) When she was accustomed to being touched, a piece of cloth or rubber band was attached to her fluke.
3) We continued this training patiently till Fuji get used to it. Finally, the attachment of artificial fin was attempted.
Training was not easy as it might sound. At the beginning of training, Fuji had strong reaction to the artificial fin. She would struggle out of the trainer's hand and swim away.
However, the trainers took time to train her patiently. We never forced her the training. Now she became perfectly fine with the fin. Her training sessions are open to the public at the Dolphin Lagoon Pool.

Rehabilitation training (2nd stage)
When she became comfortable with the artificial fin, we started the next stage of rehabilitation training. The first step of this stage was swimming training with the fin. Even though she got a new fin, she did not start swimming immediately. She was used to just floating in the pool and being hand-fed by the trainers. She got tired easily as we often saw her resting.
1) Trainers threw fish into the pool to let Fuji swim after the food.
2) Two trainers called Fuji using underwater bells at the both ends of the pool. She was trained to swim back and forth between them.
3) Next step was to make Fuji swim from 4m deep tank into 50cm shallow pool. In the shallow pool it was much easier for the trainers to attach the fin to Fuji.
4) This last step took a long time, about three months. The shallow pool was an unfamiliar place for Fuji so she was scared. Though she could enter to the shallow pool, she felt uncomfortable and swam back to the main tank soon.
Trainers attracted Fuji to the shallow pool with the food. Now she can not only let trainers attach the artificial fin but also receive health check in the shallow pool.
When she got used to wearing the fin, we began to train her to jump and touch a target. The training was started without attaching the artificial fin. When she learned to jump without the fin, we started training with the fin attached.
Fuji became able to jump strongly and touch the target with the cowling model. Now she can also do high jumps. We are planning to start training for measuring her swimming speed.

Future Plans
So far we have developed several versions of the artificial fin. However, the newest version is not yet perfect. We still continue our research for better materials and way of attachment. We are still trying out new ideas. At the same time, the research for artificial fin might give us an insight into the function and mechanism of the natural dolphin tail flukes.

　In order to achieve our goals, we would like to get more people involved and ask for diverse opinions.
Please come and visit Fuji at the Lagoon Pool. We welcome your visit and will be happy to answer your questions.

Dolphin Lagoon