A slender, spiny-rayed fish with 2 separate dorsal fins and a large mouth, the upper jaw extending about to the hind edge of the eye. The hind edge of the bone just ahead of the gill cover is strongly saw-toothed, and the tail fin is dintinctly forked.
Can be distinguished from the closely related walleye using these characteristics: Sauger has distinct dark blotches or “saddle marks” on sides; has dark spots on the first dorsal fin; first dorsal fin lacks dark blotch near the base of the last few dorsal spines; scales are present on cheek; any white blotch on the lower lobe of the tail fin is absent or reduced. Sauger are generally smaller than walleye.
Sauger occasionally interbreed with walleye where their ranges overlap to produce “saugeye.” The hybrid shares characteristics of both parents, making identification difficult.