An inclined-screen trap was installed on the Carp Lake River, Emmett County, Michigan, in the spring of 1948 and has been in almost continuous operation since that time. The major goal of this project--a precise determination of the length of the larval life of the sea lamprey--was not attained because of the contamination of the stream above the dam with spawning lampreys. The lampreys and other fishes collected in the trap did, however, provide extensive and valuable biological information. The present report documents much of the information, largely in tabular form, accumulated over the operating seasons, 1948-49 through 1957-58; the amount of detail has been varied according to the importance of the topic under consideration or the amount required to bring out a particular point.