The endangered Hawaiian monk seal population has reached a milestone — it surpassed 1,500 for the first time in more than 20 years.

Monk seal researchers from the National Oceanic and Atmospheric Administration announced the milestone earlier this week, confirming that the total estimated population for 2021 was at 1,570, up from 1,435 in 2019.

The increase marks a turnaround for the seals, which had prior to 2013 experienced a population decline of more than 4% per year in the Northwestern Hawaiian Islands

“It’s been a long time coming,” said Michelle Barbieri, lead scientist of NOAA’s Hawaiian Monk Seal Research Program. “It’s been the culmination of many years of monitoring, developing and acting.”

Barbieri credited a hands-on conservation program that works to save the lives of individual animals, especially adult females that are important to continuing the monk seal population. This includes everything from saving malnourished pups to disentangling them from marine debris, reuniting separated moms and pups, and translocating seals to increase their odds of survival.

The growth was widespread, having increased in both the NWHI within Papahanaumokuakea Marine National Monument and the main Hawaiian islands, with a current ratio of nearly 1,200 in the former and close to 400 in the latter.

Based on estimates, the monk seal population grew at an average rate of 2% annually from 2013 to 2021.

They are, however, still listed as an endangered species under the Endangered Species Act, and remain protected by state and federal laws. In order to be downlisted from endangered to threatened, population levels of monk seals would have to be more than double the current number.

Monk seals still face numerous threats, which include intentional harm by humans, marine debris entanglement, diseases such as toxoplasmosis, and loss of habitat due to climate change.

NOAA has monitored the monk seal population for nearly 40 years, but had to cancel their survey in the Northwestern Hawaiian Islands in 2020 due to the COVID-19 pandemic. They were able to return in the summer of 2021, with numbers that confirmed the new milestone, and recently returned to conduct this year’s population survey.

During peak pupping season, NOAA reminds the public to give mom-pup pairs at least 150 feet of distance and to call in sighting to help them track the seals to the marine wildlife hotline at 888-256-9840.