Scripps Institution of Oceanography

The story of the spawning habits of the grunion has been worked out in some detail by Thompson (1919) and Clark (1925). Their data are entirely sufficient to give the general picture. However, there is little in their data which points toward the mechanism by which the timing of the spawning runs of the grunion is controlled. Notably lacking are continuous observations on runs, to determine exactly when they do and do not occur. This information would appear to be essential if the controlling factors and mechanism of timing are to be found. In the present work the results of continuous observations on grunion runs for a period of three years are given. The times of observed runs are correlated with various physical phenomena, in order to suggest which of these phenomena may be important agents in the timing. Since these observations extended over a period of three years, it is natural that many new details about the general life history of Leuresthes have come to light.