An angler opinion survey was begun at Castle Lake, Siskiyou County, California, during the summer of 1957. Approximately 200 anglers were asked standardized questions in an attempt to determine how the opinions of trout fishermen about species, minimum acceptable size, and size-number balance could best be obtained. The sample of anglers was too selective to yield data of broad application. However, the technique of questioning was developed sufficiently to permit its use on a more random sample. Visual aids were used to break through prestige considerations and cliches and obtain true preferences.