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Dispatches from Point Blue’s field station on the Farallon Islands National Wildlife Refuge

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Humpbacks on the Rise

July 27, 2017

Photo by Mike Johns

I am sure most of you reading this are well aware of whaling and the devastating consequences it had for whales around the world. San Francisco Bay and the surrounding area has a long history of whaling. Roger Thomas, who runs whale watching trips on the Salty Lady, recalls when whales were still being dragged under the Golden Gate Bridge in the late 1960s. Fortunately, in 1971, whaling ended in the bay following pressure from declining numbers. Later in 1986, the International Whaling Commission (IWC) placed a ban on commercial whaling.

Suspended humpback whale at Point San Pablo Yacht Harbour prior 1971

Although it has taken them a long time to bounce back, humpbacks are on the rise and recovering strongly from whaling in the North Pacific Ocean. At the end of commercial whaling, a worrying estimate of only 1,400 individuals remained, but today, numbers have increased to around 20,000. The increase in numbers is truly reflected in the annual humpback whale counts around the Farallones.
Rplot
Fig. 1. Annual sum of humpback whale counts from 1973 – 2016

In my last blog, I wrote about our record breaking whale numbers around the Farallones. Of the 251 whales spotted on “the most amazing whale day ever”, at least 216 where humpback whales. I decided to look further back into the data and found some exciting results. Over 44 years, the overall trend shows an increase in the number of whales sighted around the island and since 1993, the average annual count of humpbacks around the Farallones has increased by almost 10 times! (Fig. 1). In the 1970s, less than 50 individuals were typically seen in a year, yet last year, 2,351 whales were counted. You might also notice that there is variation in numbers of whales sighted per year. This is because humpbacks may change their feeding locations from year to year. The population of humpbacks that visit the Farallones migrate from their breeding grounds in Mexico and Central America, but feed in a variety of areas in the North Pacific (Fig. 2).
Fig. 2. Map of North Pacific Ocean with feeding and breeding grounds, and migration routes of humpback whale populations that are seen from the Farallones. SEFI marks location of South East Farallon Island. Figure modified from NOAA (2017).

Despite their amazing come back, humpback population estimates have not reached their original numbers and they are still at risk to entanglements, vessel collisions and toxic spills. Why not educate yourselves on how to prevent these threats for whales and all other ocean creatures?

-Cerren Richards (Point Blue Farallon Intern)

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