RIVERDALE, N.D. (AP) -- A large increase in the number of young pallid sturgeon from the Garrison National Fish Hatchery is keeping wildlife officials busy this month as they apply identification tags to the endangered fish.

The hatchery will release about 130,000 fry and another 72,000 young fish this year, compared with about 15,000 a year ago, said Rob Holm, the hatchery's project leader.

''It's been phenomenal this year," Holm said. ''This has been our most successful year here by far."

Holm and other U.S. Fish and Wildlife officials are expecting crews from agencies in Montana, South Dakota and Missouri to help them place identifying tags on about 40,000 young sturgeon this month.

The tags will help scientists track the survival of the endangered species in the Missouri River system.

The peculiar-looking fish, with bony plates and long snouts, can grow to 100 pounds, a length of 6 feet and live 60 years. Dam construction on the Missouri changed much of the sturgeon's habitat, and the fish has been on the endangered species list since 1990.

Officials are planning to release the young fish raised at the Garrison hatchery at several points along the Missouri, including areas in Montana, South Dakota and Nebraska, Holm said.

The young fish being tagged this month were hatched in June and July and are about 3- to 4-inches long. They will be identified either by small filaments or a latex implant that signifies where the fish came from and the year they were released.

The large number of fish raised in Garrison is stressing the amount of space at the hatchery, said Steve Krentz, a Fish and Wildlife Service biologist who leads the nation's Pallid Sturgeon Recovery Team.

''They grow fairly fast the first month or two and kind of exponentially overcrowd their space," he said.

The success of the breeding program is partly due to experience that scientists are gaining in managing the pregnancy cycles of female sturgeon, Holm said.

The fish develop eggs on their own, but do not ovulate in a captive environment. Researchers must give the egg-producing females hormone injections to spur the process, Holm said.

''I think a lot of it's good fortune ... but obviously we're getting better with our spawning techniques," he said. ''You have to have all the stars aligned right."

Officials will continue to monitor the fish for signs of Missouri River Sturgeon Iridovirus, which can compromise the immune system, Krentz said.

''It's endemic to the population. The main issue is trying to suppress its expression while the fish are in captivity," he said.