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The intent of the present Windy-Gap work program includes determining the factors that affect the survival of Colorado squawfish and humpback chub beginning after hatching from the egg and during spawning and their first year of life, Knowledge of these limiting factors would then be used in an attempt to increase the popula tion size of these species, perhaps to the ultimate extent that the endangered species designations can be removed . The specific objectives of the Windy-Gap work plan are: 1) to locate and describe reproductive habitats for Colorado squawfish and humpback chub in the Grand Junction area 2) to locate and quantify rearing areas for young Colorado squawfish and humpback chub 3) to identify the major factors that affect the survival of Colorado squawfish and humpback chub during the first year of life 4) to modify river backwaters and gravel pits, in the Colorado River between Debeque Canyon and the mouth of the Green River, in a way that might enhance the su rvival of endangered fishes 5) to evaluate natural and modified river back~ters as habitat for young Colorado squawfish and humpback chub, and 6) to determine-the extent that Colorado squawfish and humpback chub move within the Colorado River and its tributaries. These objectives are largely interrelated and the achievement of some is prerequisite to the successful completion of others. The objectives consists of two major work elements; (1) movement, spawning, and rearing studies (objectives 1, 2, 3, and 6), and (2) backwater and gravel pft investigations (objectives 4 and 5). Although a distinction is made between these work elements for the purpose of clarity, it is recognized that work elements themselves are also interrelated. This is the second annual report on the Windy-Gap studies being conducted by FWS. Additional details on methodology and 1982 results can be found in Miller et al. (1983). Investigations of Colorado squawfish during 1983 were carried out in the Colorado River between Palisade, Colorado and the upstream region of Lake Powell, Utah; the lower 3.5 miles of the Gunnison River; the lower 20 miles of Yampa River; and the Green River from its confluence with the Yampa downstream to the Colorado River (Figure 1). The main emphasis. of tris study on the main Colorado River was a 200 mile section of river which was divided into three reaches; the upper reach between Palisade, Colorado and Westwater Canyon, Utah; the middle reach between Westwater and Cataract canyons; and the lower reach below Cataract Canyon, which consists almost entirely of waters impounded within Lake Powell (Figure 2) . 2