Mystery absence of humpback whales in Hawaii has experts scratching heads

The giant whales are an iconic part of winter but have been slow to return as they usually make the trek to the islands from November through May

Humpback whales have been slow to return to Hawaii as December usually marks the start of the season, experts say.

The giant whales are an iconic part of winter on the islands and a source of income for tour operators. But officials at the Humpback Whale Marine Sanctuary said theyve been getting reports that the whales have been difficult to spot so far.

This isnt a concern, but its of interest. One theory was that something like this happened as whales increased. Its a product of their success, said Ed Lyman, a Maui-based marine biologist and response coordinator for the sanctuary.

What Im seeing out there right now I would have expected a month ago, said Lyman, who was surprised by how few of the animals he saw while responding to a call about a distressed calf on Christmas Eve. Weve just seen a handful of whales.

It will be a while before officials have hard numbers because the annual whale counts dont take place until the last Saturday of January, February and March, according to former sanctuary co-manager Jeff Walters.

They dont necessarily show up in the same place at the same time every year, Walters said.

More than 10,000 humpback whales make the winter journey from Alaska to the warm waters off Hawaii, traveling in groups of three or four, to mate and give birth among larger pods. The season for humpbacks usually runs from November through May, as whales swim along the archipelago. The first whale of the season was spotted on 29 September by a National Oceanic and Atmospheric Administration vessel.

The plankton-eating animals are protected as an endangered species, and federal law prohibits approaching within 100 yards of them by boat. Fewer than 10% of humpbacks original population remains, according to the California-based Marine Mammal Center.

Lyman said the whales absence could just mean theyre spending more time feeding in northern waters, possibly because of El Nio disruptions or because their population has gone up.

With more animals, theyre competing against each other for that food resource, and it takes an energy of reserve to make that long migration over 2,000 miles, he explained.

Other Pacific whale species struggled in 2015: humpbacks and sperm whales became entangled in nets and stranded on beaches off California; 30 whales, including fin whales and humpbacks, died in an unusual mortality event off Alaska; and 337 sei whales found dead on the Chilean coast, the largest whale stranding on record.

Read more: http://www.theguardian.com/environment/2016/jan/02/humpback-whales-hawaii-mysterious-absence