Freshwater
The freshwater environment consists of wetlands, marshlands, bogs, streams, and lakes. Animal associations reflect the integrated effects of hydrological regimes, topography, topographic gradients, sediment loads, composition and density of vegetation, and water. Large areas, such as along the lower Selawik and Noatak Rivers, the northwestern Seward Peninsula, and Kobuk River delta lowlands, contain extensive marshlands as well as lakes supporting various and abundant bird, mammal, and fish populations.
Plankton, lnvertebrates, and Fish
Copepod and cladoceran crustaceans comprise the majority of zooplankton found in freshwater habitats in this region. Many of these species are physiologically adapted to cold waters, having high rates of metabolism and the ability to produce more than one generation of offspring during the short summer period. More common genera are Daphnia, Cyclops, and Moraria.
Little study has been made of the larger invertebrates in freshwater habitats of this region. Oligochaete annelids, molluscs (both snails and bivalves), and insects (primarily chironomid larvae) are well represented.
Freshwater fish include all five species of Pacific salmon, Arctic char, inconnu, several species of whitefish, northern pike, burbot, and a number of lesser species. Inconnu inhabit only large rivers with extensive delta areas where they can feed in brackish waters. Large populations of inconnu exist in the Kobuk and Selawik River drainages. These fish migrate many miles upstream in late summer to spawning areas. Rearing and over-wintering areas are in brackish water inlets or large lakes.
King and silver salmon are found in numbers only in the southern portion of this region. A significant run of both species occurs in the Unalakleet River. A small population of red salmon that spawns in the Kelly River, a tributary of the Noatak River, is probably the most northerly population of this species. Large pink salmon runs occur in several Norton Sound rivers—the Shaktoolik, Unalakleet, Ungalik, Inglutalik, and Niukluk. Smaller stocks of pink salmon spawn in minor drainages all along the coast of this region. Chums are the most abundant salmon. It has been estimated that the run of chum salmon to the Noatak River exceeds one million fish in some years (Wolfe 1960; 1962). Most other moderate to large rivers along the coast of this region contain fair to good escapements of chum salmon. Arctic char are abundant and conduct spawning runs up many of the rivers.
[insert list of Important Animals of the Freshwater Environment]
Birds
Species of birds listed as aquatic also use upland habitats. Waterfowl, for example, will not breed where suitable upland or marsh edge nest sites are not available. Most shorebirds, even loons, have similar requirements, so the Canada goose in the Northwest Region is as much an inhabitant of moist and wet tundra as it is of fresh water, and the spotted sandpiper is equally an inhabitant of brushy uplands.
The Kotzebue Sound Subregion includes major waterbird habitats in lowlands bordering the Noatak and Kobuk Rivers, a broad lake-studded plain extending inland from Selawik Lake and along the Selawik River, and other habitats near Kotzebue Sound extending as far west as Point Hope. The breeding population of about 234,000 ducks within the Selawik-Kobuk-Baldwin Peninsula area averages about 44 ducks per square mile and is composed mainly of pintail, American wigeon, and greater scaup. This density of breeding birds is comparable to nesting on the Yukon delta. Lower densities are found in the flats of the lower Noatak River. Cackling and Taverner's Canada geese occur throughout the Kotzebue Sound area during summer and fall. Both of these subspecies of small geese have short migration routes which terminate in Washington, Oregon, and California (Figure 142).
Tens of thousands of white-fronted geese nest in the region, migrate through the northern prairies of Canada and the United States, and winter near the Gulf of Mexico. Whistling swans can be found throughout the region, nesting near lakes in the interior basins, along rivers, and adjacent to coastal lagoons. They are particularly abundant in the lower Noatak and Kobuk River valleys, where nearly 500 were counted in 1973. The only record of the whooper swan (Cygnus c. cygnus) breeding in North America was obtained in the Selawik area. Numerous other species of ducks, loons, shorebirds, and sandhill cranes nest in or near freshwater areas in the subregion. Large lakes are also used by molting waterfowl.
In the Norton Sound Subregion the most extensive and productive freshwater bird habitat is the lake-studded coastal plain on the north side of the Seward Peninsula. Units of habitat on St. Lawrence Island and in the Kuzitrin River-Imuruk Lake area are smaller but probably as productive. Other less extensive units occur near Norton Sound and in smaller river drainages. Bird densities in these habitats are somewhat higher than in Kotzebue Sound, and about 230,000 ducks, mainly pintails, scaup, oldsquaws, and scoters, nest in the subregion. Swans, Canada and white-fronted geese, loons, cranes, and shorebirds are abundant in the freshwater habitats of the subregion. Emperor geese also nest commonly on the north side of the Seward Peninsula.
The avifauna of this subregion, including St. Lawrence Island, is of particular interest to ornithologists because of the opportunities for sighting Asiatic species and because of the spectacular migration through and across Bering Strait.
Mammals
Beaver, muskrat, mink, and river otter use freshwater habitats of the region. Beaver occur only in the southern and eastern portions of the region and do not normally range north or west of the Kobuk River valley. The range of mink is similar. River otters occur mainly in the eastern portion of the region and are not normally found at the tip of the Seward Peninsula or far west of the Noatak River. Muskrats have a similar range, but it includes the north coast of the Seward Peninsula.
[Alaska Regional Profiles, Northwest Region, pp. 169-171]