Humpback whales are marine mammals known for their extensive annual migrations. They travel thousands of miles between their tropical winter breeding grounds and their summer feeding areas. Alaska’s nutrient-rich waters serve as the primary destination for North Pacific humpbacks, offering an intense period of foraging.
The Annual Migration Cycle
The timing of the whales’ arrival and departure is predictable, driven by the seasonal availability of food. The northward migration begins in the spring, with the first humpbacks arriving in the Gulf of Alaska and Southeast Alaska around late April or early May. They travel from warmer waters near Hawaii or Mexico to replenish energy stores depleted during winter fasting.
The population density peaks during the summer months, creating the most consistent viewing opportunities. From mid-June through August, the greatest number of humpbacks concentrate in bays and fjords, actively consuming large amounts of prey. This peak period provides the best chance to observe their feeding and social behaviors.
As summer ends and schooling fish dwindle, the whales prepare for their southward journey. Humpbacks typically begin migrating back to tropical breeding grounds in late September and October. While most depart by late fall, some individuals may linger until November or December before heading south.
During the winter months, from December through March, humpbacks are almost entirely absent from Alaskan waters. They spend this time in warm, shallow breeding grounds, where they mate and give birth to calves.
The Role of Alaska’s Waters
Humpback whales travel great distances to reach Alaska for sustenance. The cold, subpolar waters of the Gulf of Alaska and the Bering Sea are exceptionally productive, supporting massive concentrations of small organisms. This productivity results from the upwelling of deep, nutrient-rich water into the surface layer.
Once they arrive, the whales engage in hyperphagia, or intensive feeding. Their diet consists primarily of small schooling fish, such as herring and capelin, and euphausiids (krill). To prepare for the non-feeding winter, an adult humpback may consume up to 1.5 tons of food daily, building blubber for insulation and energy reserves.
Humpbacks are baleen whales, using keratin plates in their mouths like a sieve to filter prey from seawater. Their throat pleats allow their mouths to expand significantly, taking in thousands of gallons of water and food in a single gulp. This efficient mechanism exploits the dense schools of prey found in northern latitudes.
Key Alaskan Habitats for Humpback Feeding
Humpback whales concentrate their feeding efforts in specific geographical areas that funnel and trap their prey. Southeast Alaska, particularly the protected waters of the Inside Passage, is a major summer gathering point. Regions that consistently draw large numbers of whales include:
- Glacier Bay National Park.
- Icy Strait.
- The waters surrounding Juneau.
- The waters surrounding Sitka.
Further west, the nutrient-rich areas of Southcentral Alaska are reliable feeding grounds. Locations like the fjords and Resurrection Bay within Kenai Fjords National Park, and the waters near Prince William Sound, are frequent sites for concentrated whale activity. These sites offer deep, protected channels where small fish and krill aggregate.
The migratory route extends into the Gulf of Alaska, with populations found around Kodiak Island and the Barren Islands at the mouth of Cook Inlet. These areas, along with the Aleutian Islands, represent the westernmost extent of the summer range. The topography of these habitats helps drive prey toward the surface, making foraging more efficient.
Optimizing Whale Watching Opportunities
For those hoping to witness humpback whales, the period from July through August provides the highest probability of sightings and activity. This timeframe coincides with the peak of the feeding season, meaning the whales are constantly active and visible as they pursue prey. Tour operators in communities like Juneau and Seward report near-daily success rates during these months.
Observing the whales offers a chance to see a variety of spectacular surface behaviors. Breaching, where the whale launches its entire body out of the water, and tail slapping, where the immense fluke strikes the surface, are common displays. These actions may be related to communication, parasite removal, or simply play.
The most unique and sought-after behavior is bubble-net feeding, a cooperative hunting technique observed in Southeast Alaska. A group of whales works together to blow a ring of bubbles underwater, which creates a temporary fence that corrals schools of fish. The whales then simultaneously lunge through the center of the bubble net with their mouths open to engulf the concentrated prey.
Viewing the whales is best accomplished via commercial boat tours or ferries that navigate the concentrated feeding areas. When observing these animals, it is important to follow ethical viewing guidelines. This includes maintaining a respectful distance and avoiding sudden movements or loud noises that could disturb their natural behavior. Adherence to these practices ensures the safety of both the whales and the observers.