The humpback migration: Alaska to Maui and back

The map

The whales that winter around Maui come from feeding grounds spread across the Gulf of Alaska: Southeast Alaska’s inside waters around Juneau, Glacier Bay and Frederick Sound, Prince William Sound and Kodiak, the Aleutian Islands and the southern Bering Sea, and the north coast of British Columbia. Photo-identification has matched thousands of individual whales between those places and Hawaiʻi. A whale you photograph off Olowalu in February has a fair chance of being photographed off Juneau in July.

The routes on the map are schematic. Humpbacks do not follow a highway; they fan out across the North Pacific and converge on the islands from the north and northeast.

How far and how fast

Alaska to Maui is about 3,000 miles depending on the starting point. Tagged whales have made the trip in as few as 28 days, and most take four to eight weeks, cruising at 3 to 5 miles an hour with few stops. Pregnant females tend to leave Alaska last and arrive last, having fed as long as they could. Mothers with calves leave Hawaiʻi last in spring for the opposite reason: the calf needs to grow before it faces the open ocean.

The whole round trip, roughly 6,000 miles, is one of the longest migrations of any mammal.

Without food

Humpbacks eat almost nothing between leaving the feeding grounds and returning. They live on blubber laid down over a summer of eating up to a ton of krill and small fish a day. An adult might arrive in Maui carrying 10 tons of fat and leave in April having burned a quarter of its body weight. A mother nursing a calf converts her own blubber into 100 gallons a day of milk, which is why mothers are often the thinnest whales in the channel by spring.

How they navigate

Nobody is certain. Humpbacks hold astonishingly straight courses across thousands of miles of open ocean, within a degree or so, through currents and storms. The leading explanations are the Earth’s magnetic field, which whales may sense through magnetite in their tissues; the sun and stars; the sound of surf and seamounts carried underwater; and simple memory, since the route is learned as a calf swimming beside its mother. It is probably all of these.

What is certain is that they return to the same breeding ground year after year. A whale born off Maui almost always comes back to Maui, not to Mexico or Japan, where the other North Pacific populations breed.

The calendar

• September – October

  The first scouts

  The earliest whales, often lone adults, reach the islands in late September. Whale Trust logged the first 2025 sighting off Maui on September 21.

• December

  Whale season begins

  Numbers climb every week through November and by December the channel is full enough for daily tours. Males arrive first and start singing. The sanctuary's official season opens December 15. The first calves of the year are born in the shallows just before Christmas.

• January – March

  Peak

  The channel is full. Competition pods, singers, newborns. Volunteers count whales from shore on the last Saturday of each month.

• Late March – April

  The males leave

  Adult males and females without calves head north first, having nothing to keep them in warm water that offers no food.

• April – May

  Mothers and calves

  The last to leave. By May the calf is 20 feet long and strong enough for the crossing. By June the ʻAuʻau Channel is empty.

• June – September

  Alaska

  Eating, 20 hours a day. Bubble-net feeding in Frederick Sound, lunge feeding on herring in Prince William Sound. Then, as the days shorten, south again.

Three populations, one ocean

The North Pacific holds several distinct humpback populations that mostly keep to themselves. The Hawaiʻi population feeds across Alaska and British Columbia. A Mexico population breeds off Baja California and the Revillagigedo Islands and feeds off California, Oregon and Washington. A Central America population breeds off Costa Rica and feeds off California. A Western North Pacific population breeds near Okinawa and the Philippines and feeds off Russia. There is a little mixing at the edges, and a few whales have been tracked from Hawaiʻi to Mexico in the same winter, but the lines are old and strong. The Hawaiʻi population is the largest and healthiest of the four; the Western North Pacific and Central America populations are still listed as endangered.