The study of the fish fauna in the Muskeg River commenced in 1976 with the general objective of describing the baseline states of this resource in the watershed and providing a quantitative estimate of the significance of the Muskeg River to the fisheries of the Athabasca River system. The work was designed as a part of a broadly based fisheries investigation of the Athabasca River and intensive studies of selected tributaries in the Athabasca Oil Sands region of northeastern Alberta. The Muskeg River was the first tributary stream selected for intensive study because a portion of the drainage area lies within projected new oil sands developments and other aspects of the program have conducted intensive investigations there. An interim report on this project has been published (AOSERP Report No. 26). The present report constitutes the final report for the project.