4. Unimak Pass/Aleutian Islands

Site Overview

The chain of Aleutian Islands is a westward extension of the Alaska Peninsula. The passes between the islands in the Aleutian chain connect the Bering Sea to the Pacific Ocean and are crucial areas for species migration. A main branch of the coastal current along the Gulf of Alaska turns north through Unimak and Samalga passes into the Bering Sea. The Aleutian waters to the east of Samalga Pass have distinctively different physical and ecological features from those to the west of Samalga Pass, implying that the oceanographic mechanisms in this region of narrow passage have a significant effect on the assemblage of species in the vicinity (Ladd et al. in press).

The highly productive benthic and planktonic communities are critical to baleen whales and migratory birds. Gorgonian, hydro, soft and cup corals are distributed on the seafloor all along the island chain. Endemic to the northern Pacific Ocean, Atka mackerel thrive in this area and nest nearshore. Pollock spawn here as well. This priority area is home to Pacific Ocean perch (Sebastes alutus), rockfishes, halibut and Pacific cod.

Leatherback sea turtles are also sighted in the region. These myriad islands are where the majority of Alaska’s tufted puffins (Fratercula cirrhata) build their nests. Kittiwakes (Rissa spp.), Storm petrels (Oceanodroma spp.), cormorants (Phalacrocorax spp.) and murres (Uria spp.) are often seen hovering over the waters around the Aleutian Islands. The endangered Short-tailed albatross has also been sighted along the island chain. This area is an important migration corridor for shearwaters, alcids (puffins) and cormorants, and a major wintering area for auklets.

Some six hundred sea otters continue to roam the area’s kelp forests, but the population across the Aleutians is declining (Doroff et al. 2003). Steller’s sea lions reside on the islands and forage in coastal waters. They have approximately 20 identified haulouts and 10 rookeries in the PCA, around which fishing restrictions are implemented. This is an important migratory pass for cetaceans, especially gray, fin (Balaenoptera physalus) and humpback whales.