Glacier Bay & Icy Strait Humpback Whale Population Monitoring: 2022 Update

    Photo courtesy of Humpback Whale Monitoring Program

    Glacier Bay, Alaska (KINY) - Migratory humpback whales use the waters in and around Glacier Bay National Parkand Preserve (GBNPP) in southeastern Alaska (SEAK) as a spring, summer, and fall feeding habitat.

    The majority of these whales spend the winter breeding season in Hawai’i but at least 10% migrate to Mexico.

    By the mid-20th century, commercial whaling had decimated these populations, however they have since recovered to the point that in Southeast Alaska, only the Mexico population remains listed as threatened under the Endangered Species Act.

    Most whales return year after year to the same feeding areas where their mother brought them as a calf and this strong maternally directed site
    fidelity has driven population growth over time.

    This report summarizes results from GBNPP’s humpback whale monitoring program in Glacier Bay and Icy Strait (GB-IS) in 2022, their 38th consecutive year of consistent data collection. The initial impetus for this program stemmed from concern in the 1970s that increased vessel traffic in Glacier Bay may have caused many whales to abandon the bay (Jurasz & Palmer 1981).

    Key Findings

    • The total number of whales in Glacier Bay-Icy Strait (GB-IS) was similar to 2021. In Glacier Bay, abundance increased compared to 2021, while in Icy Strait, abundance decreased.
    • Thirty-one of 66 adult whales (47%) with a history of strong site fidelity to GB-IS were missing and most are presumed to have died during or after the 2014-2016 Northeast Pacific marine heatwave (PMH).  
    • The monitoring program documented six mother/calf pairs and a declining crude birth rate (CBR) since 2020 (2020: 7.4%; 2021: 6.5%, 2022: 3.6%). Although calf production appeared to be rebounding in 2020 following sharp declines during and after the PMH, it remains far below the pre-PMH mean CBR of 9.1%.
    • Juvenile survival appears to be increasing after an abrupt decline during and after the PMH.  
    • Relatively high residency and low transience rates in 2019-2022 presumably reflect favorable feeding conditions in GB-IS in contrast to PMH years.
    • The rate of emaciation (16%) appeared to be lower in 2022 than in recent years and reverses a pattern of increasing emaciation.
    • In February 2022, adult female #235/”Spot” (age ≥49) was found dead near Angoon and a necropsy revealed that she likely died after being hit by a large vessel.
    • The monitoring program opportunistically documented forage fish, especially sand lance, but annual forage fish monitoring is needed to systematically assess whale prey trends.   

    Read the full report here.

    Below: The study area (Photo courtesy of Humpback Whale Monitoring Program)

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