Humpback Whale Population 101

The Sanctums research vessel waits for a whale to surface. Courtesy E. Lyman – HIHWNMS/ NOAA Permit # 14682

Who says Hawai‘i doesn’t have seasons? Starting around the holidays, our eyes linger on the horizon, waiting for that first humpback whale sighting. When it happens, we shout for joy (well OK, some of us do), and just like that first snowflake elsewhere, we know that winter is here.

And, for the scientifically and conservation minded, what better time to brush up on the health of this treasured species?

During the Northern Hemisphere winter, some 20,000 humpback whales (Megaptera novaeangliae), or koholā in Hawaiian, migrate nearly 3,000 miles south from their feeding grounds in cold nutrient-rich waters ranging from the coast of Northern California through the Bering Sea to Alaska. The whales seek the warmer waters of Hawai‘i, Mexico, Costa Rica and the islands of Southern Japan, where they spend the winter mating and giving birth.

The fun thing about Hawai‘i is that it is the only U.S. state where humpbacks mate, calf and nurse their young — which means we can observe their amazing acrobatic feats, such as the breach and my favorite, the tail slap.

A scared tailstock from a past entanglement. Courtesy E. Lyman – HIHWNMS/ NOAA Permit # 15240

Humpbacks were listed as endangered in 1970 due to the worldwide decimation of the population from decades of commercial whaling. Due to international whaling bans, treaties and domestic regulations, the population in the North Pacific has experienced a comeback. The Hawaiian Islands Humpback Whale National Marine Sanctuary was created by Congress in 1992 to protect humpback whales and their habitat. While on Kaua‘i the official sanctuary boundaries are on the North Shore, whales can be seen almost daily around the island during peak whale season (January-March).

How many whales are here today? Imagine how difficult it must be to determine whale population numbers on such a wide-ranging species that migrates some 3,000 miles! Indeed, there hasn’t been a whale census for the North Pacific population since 2006, when SPLASH, an international cooperative research project, was completed.

NOAA staff is seen here using cameras on the end of poles to document the health of the entire animal. Courtesy J. Moore – HIHWNMS/ NOAA Permit # 15240

Structure of Populations, Level of Abundance and Status of Humpbacks (SPLASH) involved more than 400 scientists in 10 countries from 2004 to 2006. The research included taking thousands of fluke identification photographs and utilizing scientific methods to estimate abundance of whales. The fluke, or the underside of the tail, is used to fingerprint individual whales, allowing for comparison with other researchers across the ocean.

The North Pacific humpback whale abundance was estimated to be just under 20,000 in 2006, representing a “dramatic increase in abundance from other post-whaling estimates for the overall North Pacific…” About 50 percent of this population was estimated to winter in Hawaiian waters, and independent “mark and recapture” studies for Kaua‘i confirmed the Hawai‘i population to be approximately 10,000 individuals.

Other areas of important humpback research are still conducted worldwide. This includes research on whale songs, mating patterns and behaviors, and whale response to underwater noise (e.g. from ships).

Ruby Pap

Within the sanctuary, whale rescue expert Ed Lyman focuses on monitoring the health of the population. Health and threat assessments document everything from emaciation, wounds and entanglements, to signs of ship strikes. By monitoring whale health, Lyman says we can “keep a finger on the pulse of the population.” But in terms of understanding the current population numbers, another census, perhaps a mini-SPLASH is warranted, which would require more funding and coordination.

In the meantime, the community can play a very important part in ensuring the health of the humpback whale population, by participating in the ocean count and reporting whales in distress. NOAA has a hotline number to report these incidents: 888-256-9840. If you see a distressed whale, do not take matters into your own hands, said Lyman. “More times than not (this) has not worked out well for the human or the whale,” and it is illegal to do it in U.S. waters.

• Ruby Pap is a Coastal Land Use Extension Agent at University of Hawai‘i Sea Grant College Program. She can be reached at rpap@hawaii.edu.