The population of Hawaiian monk seals — one of the world’s most critically endangered marine mammals — has been increasing 3 percent a year for the past three years, federal wildlife officials said Tuesday.

There are now about 1,400 of the seals in the wild, said Charles Littnan, lead scientist of the Hawaiian Monk Seal Research Program at the National Oceanic and Atmospheric Administration.

“This is phenomenal, hopeful news for the population,” Littnan told reporters. “Yet we have a long way to go to recovery.”

The population has experienced increases in the past, including the mid-2000s, but Littnan characterized those as minor blips.

Hawaiian monk seals declined in numbers for years, most recently as juveniles struggled to compete for food with large fish and sharks in the remote Northwestern Hawaiian Islands, a mostly uninhabited stretch of tiny atolls which includes Midway.

Sharks also attacked recently weaned seals at French Frigate Shoals, one of the chain’s most pristine atolls.

At one point, only 1 in 5 juveniles in the Northwestern Hawaiian Islands lived to adulthood.

Littnan said more juveniles are now surviving in part because of programs like those that disentangle seals from marine debris and take malnourished young seals to a Big Island seal hospital to nurse them back to health.

Littnan said about 30 percent of the Hawaiian monk seals alive today survived because of those programs.

He also attributed the rebound to broader environmental changes, such as El Nino, which is a periodic warming of parts of the Pacific that changes weather globally. El Nino patterns can help boost the food supply for the seals, which eat squid, eels, crab and other marine life.

The population in the Northwestern Hawaiian Islands is estimated at about 1,100. The population in the main Hawaiian Islands, home to Honolulu and other cities, is 300. The population in the main islands was growing for many years but has leveled out and stabilized, Littnan said.

The monk seal population had been declining since the 1950s, when federal authorities counted 3,400 seals on Northwestern Hawaiian Island beaches. Federal officials want to return the population to that level.

Littnan cautioned that the population increase could shift radically.

“This should be a bright spark, a glimmer of hope, that thing that fuels conservation. It shouldn’t breed complacency,” he said.