Life History of Adult Commercial Fishes - Biological Survey and Developmental Experiments in the Waters of Region M-8, Upper Laguna Madre

Catch per unit effort was calculated for gill net catches from 1952 to 1961. These show that the c.p.u. for drum has declined in recent years, while that for redfish has increased. The method was tested by comparing it with commercial landings. There was good agreement for redfish and less pronounced agreement for drum. Relative abundance was calculated from returns of tagged fish. The results indicate an increase of about 33 percent in redfish populations and a corresponding increase for trout. Too little of the drum population was tagged to allow calculation. Redfish returns were tested to determine if significant differences occurred when schools of fish were tagged and when scattered fish were tagged. The results indicate that there is no significant difference between returns from numerous scattered taggings and single mass tagging. Checks were made of total mortality and sexual dimorphism of sea trout. Total mortality averages about 50 percent, or about ten times fishing mortality. Males suffered higher mortality than females.