Scientists have announced that razorback sucker fish, an endangered fish species that has recently reappeared in the Grand Canyon, is thriving and has begun to spawn.

"Razorback suckers continue to surprise us in Grand Canyon [National Park]--first with the discovery of adults after 20 years of absence, and now with spawning within the park," Brian Healy, fisheries program manager for the national park, said in a statement quoted by Live Science. "We're all hoping to see evidence that these larval fish survive to adulthood in the coming years."

Scientists aren't certain as to why the fish has returned to the area, but friendlier river conditions may be one reason. The Colorado River has gained more beaches and sandbars in the last two years since the U.S. Department of the Interior began flooding the area to rebuild sediment and habitat.

Formerly one of the biggest fish in the Colorado River, the razorback sucker fish disappeared in 1990 following the 1960s construction of the Glen Canyon Dam, which altered the local ecosystem. The razorback, which can grow up to 3 feet long and has a bony keel along its back, became endangered after its habitat was altered by the dam and by the introduction of non-native fish species.

During the last two months, biologists have found larval razorback suckers at nine locations along the river, signifying the species' return. The Colorado River is additionally a habitat for several other endangered fish species that can't be found anywhere else.

Nine adult razorback sucker fish were tagged and released in the park in March, and biologists have been tracking them.

"This exciting news suggests that Grand Canyon is becoming a significant basin-wide haven for the endangered fishes in the Colorado River," Lesley Fitzpatrick, a biologist for the U.S. Fish and Wildlife Service, said in a statement quoted by Live Science.

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