Brown trout growth became poorer over time in the Burton's Landing to Wakeley Bridge segment of the Main Au Sable, but decreased little in the other river segments studied. Brook trout growth did not change significantly in any river segment. Survival rates of second and third summer brown trout were better in both streams during the later years of investigation. Brook trout survival rates remained relatively constant.

The total trout population (standing crop by weight) generally decreased in the Main Au Sable but increased in the North Branch of the Au Sable. Brown trout populations became progressively higher and brook trout lower during the study period.

The causes for the changes noted cannot be determined with certainty because of the many alterations made in the fish habitat, fish stocking policies and fishing regulations.