The information presented here reviews what is currently known of fish ecology and production of the Athabasca Basin, and includes discussions of fish production, sport and commercial use of fish populations, and alternative opportunities for recreational fishing in the rivers of the Athabasca Basin. Fisheries management objectives for the basin rivers and data gaps in existing knowledge of fish and fisheries are also discussed. In addition, water quality criteria for the protection of fish and aquatic life have been referenced, and, where possible, stream flows which affect fish populations have been included. The Athabasca Basin accounts for 23% of the land area of Alberta. For the purposes of this report, the basin has been divided into 10 sub-basins: four mainstem sub-basins, and six tributary sub-basins. The mainstems of the principal rivers of the 10 sub-basins provide approximately 4,390 km of fish habitat which can be roughly divided as providing 1,500 km (34%) coldwater habitat (supporting mainly trout and whitefish), 2,250 km (51%) warmwater habitat (supporting mainly pike, walleye, and goldeye), and 640 km (15%) transition zone intermediate between the two. Both commercial and recreational fisheries occur within the Athabasca Basin. The commercial fish catch represents a substantial proportion of the overall harvest and total market value of the Alberta commercial fishery. The recreational fishery occurs mainly in rivers and streams, though some lakes and reservoirs provide alternate opportunities. In 1980/81, approximately 9% (26,346) of Alberta's licensed anglers resided and fished within the Athabasca Basin. The opportunities provided to sport fishermen by the basin rivers have local, regional and in some cases, national significance. The Athabasca River rises high in the Rocky Mountains, and terminates at the delta created by the Peace and Athabasca rivers at the western extreme of Lake Athabasca. Over its length, the Athabasca River grows from a torrential high-mountain stream to a silt-laden major river at its delta, and its basin encompasses virtually every temperate stream type. In its upstream reaches, the Athabasca River flows generally northeast, steadily increasing in volume as it receives flows from the Berland, McLeod, Pembina, Lesser Slave, Lac La Biche, and Calling rivers. Further downstream, in the vicinity of a series of rapids, the river receives flows from the Pelican and Horse rivers. Near Fort McMurray, the Athabasca forms a confluence with the Clearwater River, and turns to flow north through the Athabasca Oi1 Sands region. Within the oil sands, the Athabasca River receives flows from many rivers and streams, including the Steepbank, Muskeg, Mackay, Ells, Firebag, and Richardson rivers. Reaching the Peace-Athabasca Delta near Embarras Portage, the Athabasca River subsequently forms part of the Mackenzie drainage, which empties into the Beaufort Sea. Flowing through diverse and widely differing terrain, including remote alpine areas, populated urban settings, and the 1argest open-pit oil sands mining sites in the world, the Athabasca Basin is made up of a corresponding variety of waterbodies. Within the basin, each sub-basin has characteristic fish-producing capabilities, which are largely determined by the conditions which contribute to its environment. The primary features of each sub-basin and the characteristics of its lakes and rivers are summarized.