The following report is now available on the Glacier Bay National Park & Preserve web site. Please note that this report summarizes findings from summer *2016* -- stay tuned for our 2017 report. Neilson, J. L., C. M. Gabriele, and L. F. Taylor-Thomas. 2017. Humpback whale monitoring in Glacier Bay and adjacent waters 2016: Annual progress report. Natural Resource Report NPS/GLBA/NRR—2017/1503. National Park Service, Fort Collins, Colorado. https://www.nps.gov/glba/learn/nature/upload/Neilson_ etal_2017_GLBA_2016_annual_humpback_whale_report_FINAL.pdf [3.7 MB .PDF] *ABSTRACT* Migratory humpback whales (*Megaptera novaeangliae*) use southeastern Alaska as summer feeding habitat, including the waters in and around Glacier Bay National Park and Preserve (GBNPP). This report summarizes GBNPP’s humpback whale monitoring program in Glacier Bay and Icy Strait (GB-IS) in 2016, the 32nd consecutive year of consistent data collection. In June-August, we documented 164 unique whales in GB-IS, our lowest count since 2008. Counts corrected for effort reveal an increasing trend following a dramatic decline in whale abundance in 2014. We found decreases in within-year and between-year site fidelity, with over one-third (35.6%) of our ‘regularly sighted’ whales missing in 2016. We identified only one mother/calf pair, resulting in the lowest crude birth rate (0.6%) since monitoring began in 1985, and there was also a notable absence of one and two-year-old whales. Many of the whales that we observed (13%) appeared to be abnormally thin. The ‘core group’ at Point Adolphus was not sighted and many of the whales typically associated with the group were not documented. In June, whale #441 was found dead marking the end of his 45-year sighting history (1972-2016), the world’s longest for a humpback whale. There is mounting evidence that site fidelity, calving, and juvenile return rates in Glacier Bay-Icy Strait have declined substantially in recent years. Within Alaska, the long-term, consistent monitoring of humpback whales is limited to GB-IS, making it difficult to determine over what geographic scale these changes are occurring. -- Janet Neilson Humpback Whale Monitoring Program Glacier Bay National Park & Preserve PO Box 140 Gustavus, Alaska 99826 907-697-2658