ABOARD US COAST GUARD HC-130 HERCULES (AP) — A U.S. Coast Guard airplane rumbled down an airstrip on Hawaii’s Big Island, carrying hundreds of pounds of rare and precious cargo: seven endangered Hawaiian monk seals.

Federal officials found most of the young animals malnourished late last year in the uninhabited Northwestern Hawaiian Islands, the northernmost islands and atolls in the Hawaiian Islands chain.

The National Oceanic and Atmospheric Administration brought the seals to the nonprofit Marine Mammal Center on the Big Island, which nursed them back to health.

Now rehabilitated, they have started their journey home.

The Coast Guard loaded the seals on a HC-130 Hercules plane Thursday and flew them to Honolulu. The Associated Press was on the flight.

The animals will stay in a NOAA facility on Oahu until they embark on a roughly weeklong journey by boat back to their home islands. One will return to the privately owned island of Niihau.

Monk seals number only about 1,200 worldwide, and they all live in the main or Northwestern Hawaiian Islands, federal officials said.

Fewer than one in five survive their first year in the uninhabited islands because of threats including predation, entanglement and environmental changes, according to the California-based Marine Mammal Center.

All those being transported Thursday were female, said Michelle Barbieri, a NOAA veterinarian with the Monk Seal Research Program who was aboard the flight.

“We focus our efforts on female seals because they’re going to grow up and contribute to the population in the future,” Barbieri said.

While in rehab, the seals were nursed to a healthy weight to help increase their odds of survival, initially receiving fish mash through a feeding tube. They later were taught to catch and eat fish, with little human intervention, so they can hunt for themselves when they return to the wild.

“We don’t want them to become habituated to people or associate food with people,” Shawn Johnson, director of veterinarian science for the Marine Mammal Center, said in a telephone interview Friday. “So we can’t go out there and hand-feed them.”

He said he hopes the center can reintroduce 10 to 15 seals per year, which could have a dramatic effect on the population in years to come. The facility has successfully released eight seals so far, but this group was its biggest recovery and release effort to date.

Eric Roberts, a Coast Guard marine mammal response coordinator, helped bring the pups to the hospital and was there to escort them home.

“At the Coast Guard, we pride ourselves on being lifesavers, and this is a unique opportunity where we can actually contribute to saving a species,” Roberts said.

Rescuers normally transport only one or two seals at a time, making Thursday’s effort “historic” and a major boost for the overall population, which is declining by about 4 percent per year, said David Scholfield, a NOAA response coordinator for the Pacific Islands.

“These seven animals would have died,” Scholfield said. “So getting them back to health and having them potentially reproduce in the wild, and produce offspring, has a many magnitude effect.”

All seals that are released are equipped with tags so scientists can monitor their health, Johnson said.

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Follow Caleb Jones on Twitter: https://twitter.com/CalebAP . His work can be found at http://bigstory.ap.org/journalist/caleb-jones .