The average fish community in Region II lakes consisted of 36% bluegill, 18% largemouth bass, 11% white sucker, 9% yellow perch, 6% northern pike, 5% pumpkinseed, and 3% carp, plus lesser amounts of other species. The composition of the average lake in Region III was the same, +2%, except that bluegills were 41% and the percentages for carp and white sucker were reversed. Strongly piscivorous species comprised 29% of the fish biomass in Region II and 22% of the fish biomass in Region III.

The communities could not be readily sorted into natural subtypes on the basis of species composition, except that warmouth, lake chubsucker, and grass pickerel were warmwater species restricted to southern Michigan. Some of the expected relationships among environmental factors and species abundance were confirmed by factor analysis, but most of the variation in fish distribution was not explained. Cluster analysis was useful for identifying which communities were the most similar.

On the species population level, there was evidence that the proportion of large-sized fish depended on growth which, in turn, depended on density.

In general, better sport fishing was experienced in deeper, clearer, moderately vegetated lakes which had a layer of cool, oxygenated water in summer. Indices favorable to good fishing were relatively high proportions of

Piscivors (especially largemouth bass) and low proportions of bluegill, carp, and white sucker, fast growth of bluegills, and high percentages of largesized bluegill and pumpkinseed. The quality of fishing was predictable, in part, from criteria based on these characteristics.