UC San Diego Library – Scripps Digital Collection

The present study was undertaken principally in order to obtain information regarding the extent of natural mortality during the egg and larval stages of certain salmonid fishes in a small California stream, to gather essential knowledge of the spawning behavior of these fishes, and to compare the results of such observations with similar evidence from other waters.

Daily stream observations were conducted during the fall, winter, and spring of two separate seasons. The study was begun on October 15, 1948, and continued until June 1, 1949. It was resumed on October 20, 1950, and was finally concluded on May 30, 1951. During the 1950–51 season temperature and flow records were taken at a centrally located station (near the confluence of Godwood and Prairie Creeks) which was close to the spawning areas of the species being studied. The water temperatures in nearby parts of the watershed rarely varied more than 1 degree F. from those taken at this station.

The temperature (F.) was taken at midday with a standard laboratory thermometer immersed in the center of the stream. The volume of flow was calculated by means of a standard float method over a 50-foot section.