Update on abundance, trends, and migrations of humpback whales along the US West Coast

We report on the abundance and trends of humpback whales along the US West Coast where photo-identification has been conducted since 1986. Abundance was estimated for two feeding areas: California-Oregon and Washington-S British Columbia. Abundance off California – Oregon increased steadily at about 7% per year from 1990 through the 2000s when it appeared to plateau based on three different mark-recapture models. Since the late 2000s, humpback whales have expanded their occurrence on feeding grounds in a number of areas. Most dramatically, humpback whales have returned to the Salish Sea, an area they occurred prior to whaling but had been large absent until recent years. We update the migration rates of humpback whales and show that the proportion of whales migrating to different winter breeding areas changes with latitude along the US West Coast, not just between the two recognized feeding areas but also within them. The proportion of whales from the endangered Central America DPS is highest in S California and decreases to very low rates in Washington and S British Columbia. There are some indications that areas of mainland Mexico south of the main wintering areas may be more close associated with the Central America DPS. The dramatic increases in entanglements of humpback whales in 2015 and 2016 may be partly associated with changes in humpback whale occurrence. We also report on recent successes in collaborations with two efforts: 1) Wildbook, including a test of two new automated matching algorithms that are achieving 90% success rate in identifying matches within their top two choices and 2) Happywhale, a project that has created a more effective means for soliciting and receiving opportunistic photo-IDs and providing real-time feedback and information on individuals. 


Calambokidis, J.  J. Barlow, K. Flynn, E. Dobson, and G.H. Steiger. 2017. Update on abundance, trends, and migrations of humpback whales along the US West Coast. IWC Report SC/A17/NP/13 for the Workshop on the Comprehensive Assessment of North Pacific Humpback Whales. 18-21 April 2017. Seattle, WA. 18pp.

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