Humpback whale range extends into Papahānaumokuākea

It never made any sense that humpback whales would confine themselves by human political boundaries, and now research proves that indeed, they don't.

Humpbacks winter not only in the Main Hawaiian Islands, but their range extends right up the archipelago into the Northwestern Hawaiian Islands. And there are lots of whales up there.

For this bit of information, we can thank an electronic listening post called EAR, for ecological acousting recorder, about which, more here.

(Image: What an EAR looks like. Credit: NOAA.)

When these buoys were deployed to listen to marine life in the Northwestern Hawaiian Islands, researchers heard the haunting calls of humpback whales.

More of them in the middle waters of the region, and fewer in the colder waters of the northernmost atolls.

Not that they weren't there all along, but research cruises into those islands in winter are limited, because of the risk to vessels of being caught without shelter during storms. The islands and reefs beyond Kaua`i are either small or treacherous and offer little protection from powerful seas and winds. The only safe harbor in the region is the old Navy base at Midway Atoll.

Scientists with NOAA and the University of Hawai`i's Hawai`i Institute for Marine Biology conducted the research within the Papahānaumokuākea Marine National Monument.

In a press release, the team said there seem to be plenty of whales up there: “Humpback whale song was found to be prevalent throughout the NWHI and demonstrated trends very similar to those observed in the MHI.”

The research has just been published in Marine Ecology Progress series (Vol. 423: 261–268, 2011 doi: 10.3354/meps08959.)

Authors are University of Hawai`i researchers Marc O. Lammers, Pollyanna I. Fisher-Pool, Whitlow W. L. Au and Carl G. Meyer, and Kevin B. Wong and Russell E. Brainard of NOAA Fisheries' Pacific Islands Fisheries Science Center. You can find the paper online here.

They deployed nine of the EAR devices throughout the archipelago to see if they would detect whale singing, and they did.

“Song was found to be prevalent at Maro Reef, Lisianski Island, and French Frigate Shoals but was also recorded at Kure Atoll, Midway Atoll, and Pearl and Hermes Atoll,” they wrote.

Notably missing from the list are the islands nearest the main Hawaiian group, Nihoa and Necker/Mokumanamana. But the message, perhaps, is that they heard whale song wherever they put an EAR, and they just didn't put the devices at Nihoa and Mokumanamana, nor at Laysan and Gardner Pinnacles. No reason to think the whales are not there, too.

The research results add up to “strong evidence that humpback whales are common in the NWHI from late December to mid-May. Moreover, a comparison of the incidence of song on Oahu with the NWHI reveals that many locations show equivalence in song prevalence, suggesting whales use at least parts of the NWHI as a wintering ground much like the MHI.”

What isn't yet clear is whether the whales of Papahānaumokuākea are a distinct breeding group, or simply an extension of the main islands population.

And it's also not (yet) clear how many whales use the northern islands, which appear to have as much as twice as much shallow warm water habitat as the main islands.

© Jan TenBruggencate 2011