The following report summarizing humpback whale monitoring results from 2025 is now available: Neilson, J.L., C.M. Gabriele, and P.D. Bishop. 2026. Glacier Bay & Icy Strait Humpback Whale Population Monitoring: 2025 Update. National Park Service Resource Brief, Gustavus, Alaska. Glacier Bay & Icy Strait Humpback Whale Population Monitoring: 2025 Update<https://www.nps.gov/glba/learn/nature/upload/Neilson_etal_2026_Humpback_Whale_Resource_Brief-508.pdf> [3.6 MB, 11 pages] The 2026 field season (our 42nd year of monitoring) will be underway soon! KEY FINDINGS FROM 2025: * Whale abundance in Glacier Bay-Icy Strait decreased compared to 2024 and overall numbers remain ~30% lower than before the 2014-2016 NE Pacific marine heatwave (PMH). The most profound long-term effects appear to be in Icy Strait where effort-corrected abundance is 42.5% lower than before the PMH. * After a “baby boom” in 2024 we documented only six calves, yielding a below average crude birth rate (3.8%), though calf and juvenile survival appear to be rebounding following the PMH. * Lingering impacts from the PMH suggest there will be reduced humpback whale population growth in the coming years, even if feeding conditions are favorable. * Whales appeared to move around the study area more than normal in search of food, with more emaciated whales and forage fish monitoring confirming that prey were more dispersed and there were fewer large concentrated schools than in 2024. * In late June, we documented two whales with new injuries that appeared to be incisions from vessel propellers. Despite the severity of whale #2583’s injuries, it was resighted up to 53 days later and appeared to behave normally. * We confirmed the survival of #5490 (entangled in October 2023) and #2800 (struck by a vessel in Glacier Bay in August 2011) through sightings of both whales in 2025. -- Janet Neilson Humpback Whale Monitoring Program Glacier Bay National Park & Preserve PO Box 140 Gustavus, AK 99826 907-697-2658 Xunaa Káawu Aaní áwé yéi xat yatee ka ax’ yéi jixané I live and work in Huna Lingít Homeland.