Speckled Chub (Macrhybopsis aestivalis)

Status: State Threatened (1979).

Occurrence: The Mississippi River north to its confluence with the Chippewa River and the Wisconsin River north to Wisconsin Dells. This is the northern limit of their range. A map outlining Pre-1977 and 1997 to Present Distribution is available.

Aid to ID: Elongate, slender body round in cross section. Protruding nose, mouth barbels and speckled body. Pale and translucent with white belly. Sides with a silvery longitudinal stripe. Adult length: 1.7-2.1 inches (45-55mm).

Habitat: Shallow riffles of large, sand-bottomed rivers and tributaries over 160 feet (50m) wide with varying turbidity.

Food Habits: Adapted for bottom dwelling, speckled chubs are sedentary, resting quietly on the stream bottom when not moving about searching for immature insects (trichoptera, hemiptera, odonata and coleoptera), cyclopoid fish scales and some plant matter.

Natural History: Spawning occurs in May through June and continues sporadically into August. Spawn when water temperatures rise above 70^o F (21^o C). Eggs are dispersed along the bottom by currents and develop as they drift. Juveniles tend to be solitary. Lifespan is 1.5 years.

Management Considerations: Siltation may explain Wisconsin's low populations. Population densities of other fishes and amount of space available may also be factors. See summary fish management section.

Information compiled from publication ER-091.