The Yukon and Kuskokwim rivers, which flow through the refuge, support internationally significant salmon fisheries and provide habitat for at least 35 other species of fish. Tributary streams throughout the refuge contribute substantially to the salmon stocks (chinook, chum, coho, and sockeye) commercially harvested in Kuskokwim Bay, Norton Sound, and the lower Yukon River and Bethel areas. Other important species include several species of whitefish, sheefish, Alaska blackfish, burbot, northern pike, and grayling. Nearshore ocean habitats harbor Pacific herring, halibut, tomcod, and starry flounder.
During this past decade, southwestern Alaska has experienced several severe economic and social hardships as a consequence of unusually poor salmon runs. It’s believed that significant atmospheric and oceanic changes such as warmer water temperatures (up to 10oF), lighter winds, reduced currents, lower levels of nutrient upwelling, and algal blooms in the North Pacific Ocean and Bering Sea during 1997 and 1998 had profound effects on the entire marine ecosystem, resulting in a reduced food base for developing juvenile and maturing adult salmon. Besides the lack of fish, other anomalies have been noted; later run timing, smaller than average fish, altered migration pathways, reports of higher incidences of parasites and signs of increased predation. These conditions demonstrate how complicated ecosystems can be, and that far-off environmental influences can have significant implications on this remote refuge.
The subsistence harvest of salmon is essential to the culture and livelihood of indigenous populations inhabiting the refuge. On an annual basis the subsistence harvest of salmon exceeds 100,000 fish.
The vast size, remoteness, and fluvial diversity of the Yukon and Kuskokwim river drainages presents tremendous challenges in determining accurate salmon escapement numbers. Successful management requires accurate and timely knowledge of migration periods, run strength, and established escapement levels. Within these drainages are numerous projects operated individually by agencies or organizations, or through cooperative efforts. Unfortunately, considering the complexity of the systems, comprehensive information is generally deficient regarding the abundance and in-season dynamics of local salmon spawning populations. Any addition to the existing inventory of knowledge would make a significant contribution to the overall management of the aquatic resources.
Perpetuating healthy salmon runs is essential for the following reasons: 1) local people rely heavily upon the abundant aquatic resources for subsistence use, sustaining cultural values, and providing incomes, and 2) adequate salmon escapement is crucial for maintaining ecosystem health. Decaying salmon carcasses provide “marine derived nutrients” which are linked to both aquatic and terrestrial ecosystem productivity levels. The following studies are gathering data to help us better understand the potential of future returns of salmon into refuge streams.
The refuge supports three weir operations that are managed by Kenai Fish & Wildlife Field Office. The weirs are operated on the Kwethluk and Tuluksak tributaries of the Kuskokwim River and the Andreafsky tributary of the Yukon River. The weirs facilitate Service monitoring of refuge spawning salmon stocks and other resident species, scale pattern analysis, age/sex/length, run timing and abundance data. All data are shared with ADF&G. The information is used for managing the commercial and subsistence chinook and summer chum salmon fisheries.
The Kwethluk weir is run in cooperation with the Kwethluk IRA council, which receives a contract from the U.S. Fish & Wildlife Service to man and operate the weir. A similar arrangement is made with the Tuluksak IRA council to operate the Tuluksak River weir, on another tributary of the Kuskokwim.
The East Fork of the Andreafsky River weir is operated by the Kenai Fish & Wildlife Field Office The information gathered here is used in the Yukon River Joint Technical committee U.S./Canada Pacific Salmon Treaty negotiations.
The abundance of water in the form of lakes, ponds, streams, inlets, bays, and coastal areas provides habitat for waterfowl from all four North American flyways. The refuge supports a varied population of mammals, fish, and birds which are important in maintaining the traditional subsistence way of life of local residents. Nesting and brood rearing habitats for waterfowl, shorebirds, or seabirds give the refuge national and international significance.
The Y-K Delta supports one of the largest aggregations of water birds in the world. More than one million ducks and half a million geese breed here annually, and in some summers up to a third of the continent's northern pintails can be found on the refuge. In addition, nearly 40,000 loons, 40,000 grebes, 100,000 swans and 30,000 cranes return to the refuge each spring to nest. Millions of shorebirds use the refuge for both breeding and staging. In terms of both density and species diversity, the Delta is the most important shorebird nesting area in the country, and its vast intertidal zone is the most important wetland for post-breeding shorebirds on the west coast of North America. The Delta meets all of the criteria for identifying wetlands of international importance under Article 2 of the Ramsar Convention.
Despite the reduction in geese from historical levels, the refuge still supports large numbers of ducks. Results from the 2000 breeding pair survey are currently unavailable, but historically, principal species were northern pintail, green-winged teal, and greater scaup. Mallards, American wigeon, and northern shovelers are also regularly reported in good numbers. Harlequin ducks breed in many of the watersheds draining the Kuskokwim Mountains, as well as in other suitable habitats. Common eiders are locally "common" in the vicinity of some brant colonies, while Steller's eiders are virtually extinct as a breeding species on the refuge. The formerly abundant spectacled eiders have declined precipitously over the last 25 years. From an average breeding population of about 100,000 birds in the early 1970's, the population declined to a low of about 1,800 breeding pairs in 1993. The 2000 estimate was about 2,900 breeding pairs. Sea ducks in general have been declining throughout the continent and region; long tailed duck and black scoter have been added to the refuge’s list of species of concern.
Nineteen species of raptors have been recorded on the refuge, including golden eagles, bald eagles, and peregrine falcons. The coincidence of high populations of both small rodents and hares on the refuge in 2000 may have led to the abnormally high abundance and/or productivity of several raptor species (including northern goshawk, golden eagle, snowy owl, and northern hawk owl). The Kisaralik River is among the most important areas on the refuge for nesting raptors, and supports one of the densest populations of breeding golden eagles in North America.
Bristle-Thighed Curlews Banded in Alaska Were Observed in the Hawaiian Islands