The population of endangered southern resident orcas has declined from 74 to 73 in the latest census, according to the Center for Whale Research.

The center posted on Facebook this week that it had completed its annual census estimate of the southern resident killer whale population for the National Marine Fisheries Service.

As of July 1, the population was 73 whales.

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Endangered ocean species near AK

Pictured: A pod of orcas is swimming in Chatham Strait, Alaska, on Aug. 25, 2019. (Wolfgang Kaehler/LightRocket via Getty Images)

Since July 1, 2021, three whales died while two were born, officials said. Their numbers have hovered around 73 in the past few years. Their population grew during the late-1970s, 1980s, and mid-1990s, peaking at 98 animals, officials said. The population began to trend down after that, declining from 98 to 78 whales by 2001.

The southern residents face several threats to their survival including underwater noise, pollutants and lack of adequate Chinook salmon, their primary food source.

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A study by the University of British Columbia showed this year that the killer whales have not had enough food for several years.

The National Marine Fisheries Service finalized rules last year to expand the the endangered orca’s critical habitat from the Canadian border down to Point Sur, California, adding 15,910 square miles of foraging areas, river mouths and migratory pathways.