Aleutian Islands: Species at Risk
The Aleutians are habitat for several endangered species, including Steller sea lions, sea otters, short-tailed albatross, and humpback whales. Aleutian passes are also critical travel corridors for most of the world’s gray whales and northern fur seals, which transit the passes to feeding and breeding grounds.
The seafloor habitat of the Aleutian Islands is unique and has been recorded nowhere else in Alaska or in the world. The Aleutian Islands harbor some of the most diverse and dense aggregations of cold water corals known; the density and diversity of these Alaskan corals rival tropical coral reefs.
To date, 97 species or subspecies of corals have been reported from the Aleutian Islands, and 25 of these species are believed to be endemic to the region. New coral species continue to be described from collections.
In some areas of the seafloor, corals, sponges and invertebrates are so densely packed that no seafloor is visible. Such bioherms, described as deep-sea coral gardens, are unique to the Aleutian Islands. These corals, sponges, and other living seafloor form habitat that provides nurseries, places to feed, shelter from currents and predators, and spawning areas for many marine species.
Species supported by rich deep sea coral garden habitat include rockfish, Pacific Ocean perch, flatfish, Atka mackerel, golden king crab, shrimp, Pacific cod, pollock, greenling, Greenland turbot, halibut, sablefish, sea stars, nudibranchs, octopuses, snails, crinoids, basket stars, sponges, and anemones.
For these and other species, corals form essential habitat by providing shelter, protection from currents and predators, and areas for breeding, spawning, nursing, feeding, and resting. When coral and sponge habitat is destroyed, the many species it supports also disappear.
Bottom trawl gear is by far the greatest manageable threat to Aleutian corals. The National Marine Fisheries Service (NMFS) estimates over half a million pounds of corals and sponges are hauled aboard trawling vessels as bycatch every year in the Aleutians.
Millions of seabirds find their way to the Aleutian Islands every year to nest, many of which have impressive migrations. The diversity and magnitude of the bird population in the Aleutian Islands is truly remarkable and unlike anywhere else on the globe. Puffins, auklets, kittiwakes, gulls, terns, and cormorants nest in the millions in some of the largest seabird colonies in the world.
High seas and steep shores make an ideal habitat for seabirds to lay their fragile eggs. Ancient lava flows formed porous rock formations, full of cavities and passages that provide protection for nesting birds. Much of the land area of the Aleutians is protected as the Alaska Maritime National Wildlife Refuge.
Huge colonies of kittiwakes take up residence on the steep cliffs of the Aleutian Islands. Buldir Island in the Aleutians houses one of only four breeding populations of red-legged kittiwakes in the world.
The whiskered auklet (Aethea pygmaea) is one of the rarest seabirds in the U.S. An estimated 116,000 whiskered auklets live in the Aleutians. The whiskered auklet is secretive and nocturnal and is particularly susceptible to disturbance and mortality from lighted vessels.
One of the biggest threats to nesting seabirds in the Aleutians are introduced rats. Rats have colonized some of the islands by hitching a ride from early explorers and even from modern shipwrecks. Rats prey on seabird eggs and chicks and have decimated seabird nesting colonies on several islands. Today, rat eradication and prevention programs are helping keep some of the remaining islands rat-free.
The rich and diverse flora and fauna of the tide-rips and channels around the Aleutians provide a perfect feasting ground for breeding and migrating sea-life. At least twenty-six species of marine mammals will spend some of the year swimming the seas around the Aleutian Islands.
Otters, seals and walruses enjoy the clear, cold water for feeding and the isolated, rocky outcroppings of islands for mating. Fifteen kinds of whales make the Bering Sea a destination on their migratory journey. Harbor porpoises and Dall’s porpoises frolic in the turbulent seas, surfing the waves or riding the wake of a fishing vessel.
Like the other inhabitants of the Aleutians, many marine mammals shared the hardships associated with outside discovery and exploitation. Fur seal, sea otter, and sea lion populations came dangerously close to extinction due to over-harvesting by pelt-hunters in the 18th and 19th centuries.
One cannot tell the story of the Aleutian Islands without paying some bittersweet tribute to the sea otter. Invaluable to both the subsistence-living Aleuts and the fortune seeking Europeans, this precious, extraordinary animal was threatened almost to extinction.
Sea otters often swim on their backs, especially when feeding on clams or mussels that they crack with rocks from the sea floor. They also carry their young on their chest until they are well-developed swimmers. Frequently, sea otters sleep in large kelp patches that keep them securely in place as they float on the water.
The sea otter plays a crucial role in the marine ecology of its habitat. A sea otter feeds primarily on sea urchins and other mollusks, which in turn feed on the abundant kelp. Large kelp beds are home to multitudes of fish, crustaceans, and invertebrates because they provide both protection and sustenance within their weedy walls.
Scientists have found that areas with insignificant otter populations tend to lack lush and healthy kelp beds, while, in areas of large otter habitation, kelp flourishes and hence so does marine life. It has been determined from this evidence that otters play an integral role in keeping sea urchin populations at a normal level, therefore encouraging the growth and maintenance of kelp beds, as well as the health of many marine species within the kelp beds.
Valued for their silky pelts, sea otters were hunted close to extinction by Russian fur traders and eventually hunters from all areas of the globe. Beginning in the late 18th century with Russian exploration, sea otter pelts became one of the most lucrative economic commodities found in the Aleutian Islands.
Seals and Sea Lions
Steller sea lions are the second largest pinniped inhabiting the Aleutians. They often haul themselves onto rocks and will erupt into a chorus of barking when bothered. Many a mariner has passed by an island inhabited by sea lions and been practically deafened by the belch-like song of these powerful mammals.
Aleuts hunted these animals for their skins which resulted in a diminished population, but this practice ended in 1914 when villagers began using canvas instead of sea lion pelts.
Alaska fur seals are a rare visitor to the Aleutian Islands, breeding in the Pribilof Islands far out in the Bering Sea, then swimming through Aleutian waters. These animals resemble the Steller sea lions but don’t quite match up in size. Fur seals were coveted for their silky pelts, but the practice of hunting these animals has since been outlawed.
Shy harbor seals are abundant but less often seen residents of the Aleutians. They spend much of their time out of the water but at the first sign of danger will slide back in and observe goings-on from a more secure vantage point.
Bearded seals have occasionally been spotted in the Aleutians, though it is a rare occurrence. Ribbon seals are another type of seal that are sometimes found around the Aleutian Islands. Male ribbon seals are easily identified by their stark black coloring and contrasting white bands around their neck and flippers. The rarest, least recorded species of seal found around the Aleutian Islands is the hooded seal.
Fish and the fishing industry have played crucial roles in the lives of both Aleuts and outsiders. The narrow channels and turbulent waters between the islands churn up hoards of organisms and small marine life that make this area a healthy feeding ground for around 450 species of fish.
The most important to the fishing industry are “groundfish,” a term that encompasses a wide array of species that inhabit the deeper regions near the sea floor and at the edge of the continental shelf.
Foreign fishing fleets caught large numbers of fish in the Aleutians in the 1960s and 1970s, but are now excluded with the advent of the 200 mile exclusive economic zone. The majority of fish are now caught by U.S. owned factory trawlers and freezer longliners, with a smaller proportion caught by smaller vessels that deliver to shoreside processors.
Atka mackerel is the most valuable groundfish fishery in the Aleutians. Most of the Atka mackerel catch is caught by a few large factory trawlers. Pacific Ocean perch is a long-lived rockfish that was originally targeted widely by foreign fisheries, but is now only available to domestic fisheries.
These fish are taken by trawl catcher-processors, and are a relatively valuable member of the groundfish group. Sablefish are among the top fish in terms of value, bringing in over four million dollars a year. Sablefish are taken by both bottom- and mid-water trawlers and longliners.