TOKYO >> The introduction of an animal gamete bank system to preserve the frozen sperm and eggs of rare animals is progressing at zoos and similar facilities with the aim of continuing to breed endangered species in the future. Nine facilities in various regions of Japan have already set up such banks.

The veterinary hospital at the Tokiwa Zoo in Ube, Yamaguchi prefecture, is storing the sperm of ruffed lemurs, a rare species bred at the zoo, in a tank filled with liquid nitrogren set at a temperature of minus 320.8 Fahrenheit. The sperm is kept frozen using a technique called cryopreservation.

In October, in addition to hiring a cryopreservation expert, the zoo signed a memorandum of understanding with the Japanese Association of Zoos and Aquariums, a Tokyo-based public interest group that aims to promote animal gamete banks.

“It is difficult to raise a large number of individuals of each species as our zoo area is so small. With the bank, we can contribute to the conservation of rare species,” said zoo employee Yoshitaka Kimura, who is in charge of the bank.

The system involves removing reproductive cells from the testes and ovaries of live and dead animals and storing them in the nitrogen tanks.

JAZA comprises about 140 zoos and aquariums in Japan. The organization preserves the animals’ sperm and eggs for use in artificial insemination research and eventually breeding.

The collection and preservation of gametes has been encouraged since the 1990s, led by the late Hiroshi Kusunoki, an associate professor of conservation breeding at Kobe University.

Collecting gametes requires advanced knowledge and skills. Among JAZA’s member facilities, only a center for wildlife conservation in Hino, Tokyo, and the Yokohama Preservation and Research Center were up to the task.

Gametes deteriorate after an animal’s death, so they need to be collected and stored as quickly as possible. Since it takes several days to send testes and ovaries from some areas of the nation to the two facilities in eastern Japan, JAZA asked zoos in western Japan to join the effort.

Tokiwa Zoo in Ube and Osaka Tennoji Zoo agreed.

The Osaka zoo decided in November to establish an animal gamete bank and is now purchasing equipment and making other preparations to begin animal gamete preservation this year.

The existing banks set up at zoos and other facilities in various regions have stored the gametes of about 120 species, including endangered Siberian tigers, Sumatran tigers and chimpanzees.

The effort to establish animal gamete banks was prompted by deep concern that rare species native to other parts of the world may not exist at Japanese institutions in the future.

The Washington Convention on International Trade in Endangered Species of Wild Fauna and Flora, which regulates international trade in wild animals, was adopted in 1973 and ratified by Japan in 1980. The convention has made importing animals more difficult in recent years due to animal welfare concerns; there is also concern about preventing the spread of infectious diseases.

To increase the number of animal gamete banks, JAZA is footing the bill to refill 20-liter liquid nitrogen tanks. It is also considering holding training sessions for collecting and preserving gametes.