[MARMAM] Glacier Bay & Icy Strait, Alaska Humpback Whale Population Monitoring: 2018 Update

Neilson, Janet janet_neilson at nps.gov
Wed Apr 3 16:15:01 PDT 2019

The following report summarizing humpback whale monitoring results from
Glacier Bay and Icy Strait, Alaska in 2018 is now available:

Neilson, J.L., and C.M. Gabriele. 2019. Glacier Bay & Icy Strait Humpback
Whale Population Monitoring: 2018 Update. National Park Service Resource
Brief, Gustavus, Alaska.

https://irma.nps.gov/DataStore/DownloadFile/620535 [692 K, 6 pages]


   - We documented 100 unique humpback whales, our lowest annual count
   since 2002.

   - Humpback whale abundance in Glacier Bay and Icy Strait has declined by
   >50% since peaking in 2013.

   - This downtrend trend has been most dramatic in Glacier Bay, where we
   identified only 45 whales in 2018, a 72% decline compared to our record
   high count of 161 whales in 2013.

   - We documented only one mother/calf pair in 2018 but by mid-August the
   mother had lost her calf, marking total reproductive failure for the first
   time in this 34-year study.

   - An increasing number of whales that exhibited long-term site fidelity
   to GB-IS in 2004-2013 (n = 66) have not been documented since 2013. In
   2018, over half (56%) of these well-known whales were missing.

   - For the third year in a row, we observed numerous abnormally thin
   whales, however it appears this was less common than in 2017.

   - Although our monitoring results clearly indicate dramatic population
   level changes over the past five years, we do not know if the declines in
   whale numbers represent a shift in distribution and/or increased mortality
   from 2014-2018. Efforts to locate the whales missing from Glacier Bay and
   Icy Strait in catalogs from other feeding areas (e.g., British Columbia and
   Prince William Sound) have so far yielded no matches. Through a new
   collaboration with Happywhale.com, we recently initiated expanding our
   search area to the broader North Pacific.

   - Within Alaska, the consistent, long-term, monitoring of humpback
   whales is limited to Glacier Bay and Icy Strait, although our findings are
   consistent with negative trends in abundance, reproduction, and body
   condition for humpbacks in other areas in the central North Pacific.

   - Growing evidence suggests that recent declines in humpback whales and
   other marine species may be related to the unprecedented marine heatwave
   that occurred in the North Pacific from 2014-2016.

Janet Neilson
Humpback Whale Monitoring Program
Glacier Bay National Park & Preserve
PO Box 140
Gustavus, Alaska 99826
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