The waters surrounding Alaska, including the Bering Sea, the Gulf of Alaska, and the Arctic Ocean, form one of the world’s most productive marine environments. This region features a vast continental shelf, deep ocean basins, and a shoreline stretching over 34,000 miles, creating diverse habitats. Cold, nutrient-rich currents fuel massive phytoplankton blooms, which support an extraordinary volume of marine life. Despite the frigid conditions and seasonal sea ice, this area supports species from microscopic organisms to the largest marine mammals.
Iconic Marine Mammals
The Alaskan seas host large animals. Humpback whales, recognizable by their long pectoral fins, travel from their breeding grounds near Hawaii to the Gulf of Alaska each summer. These baleen whales execute cooperative bubble-net feeding, working in groups to corral small schooling fish like capelin and herring. Their tail flukes feature unique patterns, allowing researchers to track individual migration and population health.
Orcas, or killer whales, are apex predators categorized into three ecotypes based on distinct social structures and dietary preferences. Resident orcas primarily feed on fish, particularly Chinook salmon, while transient orcas hunt marine mammals, including seals and sea lions. Offshore orcas travel farther out to sea and prey on sharks and other deep-water fish. These intelligent animals maintain complex family pods, often hunting using coordinated strategies.
The Arctic regions of Alaska are the sole domain of the Bowhead whale. Bowheads possess a blubber layer up to 1.5 feet thick for insulation, and their massive, arched skulls are strong enough to break through several inches of sea ice to breathe. As filter feeders, they use the longest baleen plates of any whale species—up to 13 feet long—to strain copepods and krill. They spend their entire lives in the Bering, Chukchi, and Beaufort Seas, following the seasonal movement of the ice edge.
Pinnipeds are prominent, including the massive Steller sea lion, the largest of the eared seals, which congregates on rocky haul-outs. Unlike true seals, the Steller sea lion can rotate its hind flippers forward to walk on land. The smaller, earless harbor seal is often found resting on glacial ice floes in protected bays, characterized by its spotted coat. The smallest marine mammal is the sea otter, which lacks blubber but maintains warmth with the densest fur, relying on invertebrates like clams and sea urchins.
Essential Fish Species
The finfish found in Alaskan waters form the foundation of the marine food web and support commercial fisheries. The Pacific salmon genus (Oncorhynchus) includes five species that utilize the anadromous life cycle, migrating from freshwater streams to the ocean to feed, and returning to their natal stream to spawn. Chinook salmon (King salmon) are the largest species, while Sockeye salmon (Red salmon) are known for their deep red flesh and reliance on zooplankton.
Chum salmon, sometimes called Dog salmon, are the most widely distributed across the state. Pink salmon are the smallest and most numerous, completing their life cycle in just two years. Coho salmon, or Silver salmon, are known for their acrobatic leaps during their upstream migration. This genus provides a major energy source for marine mammals, seabirds, and terrestrial predators like bears.
Below the surface, the whitefish population is dominated by Walleye Pollock and Pacific Cod in the Bering Sea and the Gulf of Alaska. Walleye Pollock is a semi-pelagic species that forms vast schools, feeding primarily on crustaceans and smaller fish. Pacific Cod is a demersal species, meaning it lives near the seafloor, feeding on bottom-dwelling invertebrates and fish.
Commercially significant groundfish include Pacific Halibut, a flatfish that begins life upright before one eye migrates to the other side as it matures and settles on the seafloor. Rockfish are a diverse group, with over 30 species found in Alaskan waters, including the Yelloweye Rockfish and the Black Rockfish. Many rockfish are bottom-dwellers that occupy rocky reefs and deep crevices, making them susceptible to overfishing due to their slow growth rates.
Deep-Water Invertebrates
The seafloor and deep waters of Alaska are populated by invertebrates that play a substantial ecological role and support shellfish industries. Commercially important crustaceans are led by the various species of King Crab. The Red King Crab is the most highly valued, found primarily in Bristol Bay, and is known for its large size and rich, sweet meat.
King and Tanner Crabs
Blue King Crab is found near St. Matthew and the Pribilof Islands, characterized by large claws and a blue-brown color that turns bright red when cooked. The smaller Golden King Crab, found in the Aleutian Islands, inhabits deeper waters and possesses a milder flavor. The Tanner Crab group is also significant, including two main species harvested from the Bering Sea:
- The larger Chionoecetes bairdi (Southern Tanner Crab).
- The smaller Chionoecetes opilio (Snow Crab).
Mollusks are a major invertebrate class, represented by the Giant Pacific Octopus, the largest octopus species in the world, which utilizes complex camouflage and intelligence. Various species of clams, such as the Geoduck and the Pacific Razor Clam, inhabit the soft sediments of the nearshore environment. Deep-sea corals and sponges form foundational structures in the cold, dark waters, particularly throughout the Aleutian Islands, creating complex habitats that shelter numerous fish and invertebrate species.
Coastal and Pelagic Seabirds
Millions of seabirds depend entirely on the productivity of the Alaskan seas. Species such as the Common Murre and the Tufted Puffin are specialized pursuit divers, using their wings to “fly” underwater to catch small fish like capelin and sand lance. The Tufted Puffin is recognizable by its distinctive yellow head plumes during the breeding season.
Highly pelagic species, including various albatrosses and shearwaters, spend most of their lives on the open ocean, only coming to land to breed. The Black-footed Albatross is a wide-ranging surface feeder that travels thousands of miles across the North Pacific. Gulls, such as the Glaucous-winged Gull and the Black-legged Kittiwake, are more coastal, frequently feeding by surface-seizing or scavenging near the shore. These birds serve as indicators of ocean conditions, with changes in their breeding success and diet reflecting shifts in the marine food web.