Marine Ecoregions of North America 0 50 100 200 Km 2

Home , Beaufort Sea

2 2.1 2.1.3 Point 2.1 Hope 2.1.1 2.1.4

1 Prudhoe Bay 4 3

2.1.2 2.1 2.1.4

2.1.4

2.2 Holman

Anchorage 5

2216 Marine Ecoregions of North America 0 50 100 200 km 2. Beaufort/Chukchi Seas

Level II seafloor geomorphological regions include: 2.1 Beaufort/Chukchian Shelf 2.2 Beaufortian Slope

Level III coastal regions include: 2.1.1 Kotzebue Sound 2.1.2 Mackenzie Estuarine Area 2.1.3 Chukchian Neritic 2.1.4 Beaufortian Neritic

Regional Overview a series of barrier beaches, spits, extensive deltas, lagoons, estu- This sparsely populated area, particularly well known for its aries, tidal flats and narrow sand and gravel beaches, with a low coastal oil and gas activities, is also home to 40 species of fish and coastal relief and a generally wide shelf. Minimal tidal influence significant concentrations of marine mammals like the bowhead also characterizes the ecoregion. whale, polar bear and ringed seal. The Beaufort/Chukchi Ecore- gion borders the Arctic Ocean and is shared by Canada, Russia Circulation is driven by Bering Sea water flowing northward and the United States. It is bounded by the Bering Strait in the through the Bering Strait, which strongly influences the south- southwest, permanent sea ice of the Arctic Basin Ecoregion, and ern Chukchi Sea and contributes to a summer coastal ice-free follows the coastal shelf along the north shore of Alaska and Can- zone 150–200 km wide. The ecoregion is covered with a com- ada’s Yukon and Northwest Territories to Amundsen Gulf. bination of landfast ice, stretching 20–80 km from the shore, and the rest by pack ice from October to June—a factor that Physical and Oceanographic Setting contributes to low salinities, as well as most of the biological The Beaufort/Chukchi Seas Ecoregion includes waters of the characteristics of the ecoregion. Two additional important phys- shallow Chukchi Sea (depths of 0–100 m) and Beaufort Sea, ical features worth noting are the Cape Bathurst Polynya and a which has a narrow, shallow shelf along Alaska, and a broad smaller polynya in Lambert Channel that appear in the spring. (extending 100 km offshore) yet still shallow shelf off the Yukon The Mackenzie River Delta also influences this ecoregion, par- and Northwest Territories—where depths of 10 m or less are ticularly its bottom sediment characteristics (sandy to silty), low found up to 30 km from shore. The deepest point in the east- salinity and high water turbidity. Currents of the ecoregion are ern part of this ecoregion is the Amundsen Gulf (600 m in the moderate to strong, while tidal range is small and tidal flows are center), characterized by large bays and little shallow water. weak. Sea surface temperatures in summer are below 12oC and The ecoregion’s continental slope drops steeply to the Arctic average 8oC in the southwest and along the Beaufort coast and Basin. The more coastal areas of the ecoregion are composed of colder to the north.

17 Fact Sheet the western Arctic are found in this region. Overall, however, the ecoregion has significantly lower densities of fishes and seabirds Rationale: defined by sea surface temperature and a transition between boreal and Arctic faunas than the Bering Sea Ecoregion. Surface: 446,009 km2 Sea surface temperature: <12°C (summer), 8°C (average) in the southwest and along the Beaufort coast Human Activities and Impacts Major currents and gyres: Cape Bathurst Polynya. A smaller polynya in Lambert Channel appears The ecoregion is well known for its coastal oil and gas activities, in the spring. particularly on Alaska’s North Slope along the Alaskan Arctic Depth: shelf (roughly 0–200 m): 88%; slope (roughly 200–2,500/3,000 m): 12%; abyssal plain (roughly 3,000+ m): 0% Note that the deepest point in the Canadian area of this region is the Coast, which provides a major source of employment and income Amundsen Gulf (600 m in the center). for the state. The region’s harsh environment makes it unsuitable Substrate type: sandy to silty, sand and gravel beaches for most other economic activities. Although there have not been Major community types and subtypes: seasonal sea ice, polar and subpolar communities, coastal major reports of damage to marine ecosystems from activities wetlands and delta communities associated with the oil and gas exploitation, new and renewed 2 8 Productivity: moderately high (150–300 g C/m /yr), but only in the summer when the ice melts interests in exploration—within Arctic National Wildlife Refuge Species at risk: polar bear, bowhead whale, beluga whale, and gray whale and offshore in the Canadian Beaufort Sea, for example—are Human activities and impacts: oil and gas, commercial fisheries, mining believed by many to be a cause for concern.

8 On the basis of bathymetry and productivity, this region has been partitioned into a separate low productivity Beaufort Large Marine Ecosystems (LME) and shallow, moderately high productivity Chukchi LME. The LME delineation of this heterogeneous region may therefore be more useful for certain purposes. The coast is sparsely populated, predominantly by small communities of Alaskan native peoples, Inuvialuit and other indig- enous groups. Subsistence use of coastal resources is particularly Biological Setting important to these communities and includes nearshore harvest- In Arctic terms, this ecoregion can be considered of moderately ing of salmon and other fishes, invertebrates and marine mam- high biological productivity due mostly to the mixing of the mals (including seals and Steller sea lion, walrus, bowhead whale freshwaters from the Mackenzie River with the salt waters of and polar bear). In the US northern Pacific and western arctic the Beaufort Sea. However, its productivity is lower than many ecoregions (1, 2, 22 and 23) two out of 35 federally fished stocks other portions of the Pacific or Atlantic Oceans. Sea ice is the are overfished (NMFS 2007). most important seasonal feature affecting the ecoregion’s fauna. Retreating sea ice in early summer contributes to plankton blooms that provide the major productivity for the ecosystem. Most marine mammals are ice-associated, following the advance and retreat of the sea ice from the Beaufort and Chukchi Seas through the Bering Strait and into the Bering Sea.

The ecoregion has relatively high fisheries production and provides habitat to 40 species of fish, including capelin, Pacific herring, Greenland cod, Arctic cod, species of the genus Coregonus such as cisco and whitefish; and sea urchins, mussels and mol- lusks, sea cucumbers, sea stars and anemones. It also has significant concentrations of marine mammals, such as bowhead and gray whales, polar bear, and ringed and bearded seals. The Beaufort/Chukchi Ecoregion includes the northern extent of some north Pacific boreal fauna—for example, salmon, Pacific herring, walleye pollock—especially in the Chukchi Sea. The Mackenzie Delta provides a very important wetland and migra- tory bird habitat for species such as king eider, long-tailed duck, scoters, mergansers, scaup, loons, geese (Chen, Branta and Anser species) and shorebirds such as red-necked phalarope. The only The thick-billed murre, one of the most common seabirds in Canada’s North, nests in large colonies on sheer cliffs too breeding populations of thick-billed murre and black guillemot in hazardous for terrestrial predators. © Nikolay Konyikhov/AccentAlaska.com

18 Marine Ecoregions of North America The bowhead whale is one of the two species of right whales and is commonly found in shallower waters and near pack ice. Photo: Flip Nicklin/Minden Pictures