PITTSBURGH - Zoo officials trying to establish North America's first elephant sperm bank have been slowed by bureaucratic hurdles but hope South African officials will approve shipping frozen elephant semen to the United States in about a month.

Officials at the Pittsburgh Zoo & PPG Aquarium have had difficulty getting export and import permits for 16 liters of semen being stored in the National Zoo's BioBank in Pretoria, South Africa, the Pittsburgh Tribune-Review (http://bit.ly/qS5twH) reported Monday.

"It is taking longer than we hoped, but we knew when we started that it had not been done before," said Barbara Baker, president and chief executive officer of the Pittsburgh zoo.

Scientists collected the samples last year as part of what's called Project Frozen Dumbo, a two-year international effort to help preserve elephants and breed them in captivity without having to ship animals from zoo to zoo.

The ZooParc de Beauval in France collected its semen samples in 2009 and has already set up a sperm bank in Europe as part of the international effort is being led by Thomas Hildebrandt, head of reproduction at the Leibniz Institute for Zoo and Wildlife Research in Berlin. Semen for the North American bank was collected only last year, which is why the effort is lagging behind Europe's, Pittsburgh zoo spokeswoman Connie George said.

The initiative is especially important because the elephant population in captivity in North America consists largely of animals past prime breeding age, which George said is from the late teens through the 20s. Elephants can live into their 50s, though that's rare due to poaching and other issues, she said.

"The population of elephants in North America will be depleted in 40 years if we don't bring in new bloodlines," George said.

Leibniz scientist Frank Goeritz is working as a reproductive consultant for the Pittsburgh Zoo and said the problem with getting approval to ship the sperm is that it's never been done here before.

"The law and all these guidelines are different from country to country," Goeritz said. "The problem is there is no standard protocol developed because it's a groundbreaking project."

Once South African scientists get approval to ship the semen, the US Fish and Wildlife Service must OK bringing it into the country, agency spokesman Bill Butcher said. The US agency must determine whether the material would promote the "propagation or survival" of elephants.

Baker said she expects the South African government to approve the shipment within a month. She traveled to South Africa two weeks ago on a trip to bring three elephants to the United States and had a chance to inspect the semen. She said it is in "excellent condition" and is expected to last several years if properly stored.

Once the semen specimens arrive, Baker said some will be stored at the zoo and some will be sent to the zoo's International Conservation Center about 60 miles (100 kilometers) southeast of the city. The zoo plans to build a cow and calf complex there, which Hildebrandt, the German scientist, will also use as his North American headquarters.

The samples are believed to be enough to inseminate 300 females. The material was gathered during a $125,000 expedition last year in which elephants were tranquilized. An anonymous donor financed the trip, and the Pittsburgh zoo doesn't plan to charge other zoos for the semen.

"We wouldn't put a price on an elephant," George said.