Combined Results of 34 Published Tracking Studies

Conventional wisdom paints a picture of torpid, near-hibernating smallmouths in stream environments during winter, especially up north. “In our radio-telemetry work, we did not observe any long-distance movements once smallmouths had completed their fall migration to their overwintering habitat,” Lyons and Kanehl observed. “However, all of the six fish we were able to track throughout winter displayed extensive and regular short-term movements, despite water temperatures that were consistently less than 33.8°F.” Even in water that would probably be frozen if not moving, smallmouths may become active on a daily basis.

Spring Movements

“Many river-dwelling smallmouth bass populations moved into tributaries to spawn in spring when water temperatures exceeded 50°F,” Lyons and Kanehl declared, referring to a variety of studies. “These tributaries comprise important summer nursery habitat for young-of-the-year fish. In the Des Moines River (Iowa), some adult smallmouth bass moved more than 3 miles into tributaries to spawn, whereas other adults spawned in the river. In the Columbia River of south-central Washington, tagged adult smallmouth bass moved out of the main river in May to spawn in tributary sloughs and backwaters, remaining there until July or August. Some recaptured individuals had moved up to 38 miles to find suitable habitat.”

Study after study reveals that smallmouths in rivers tend to be far more mobile than smallmouths in lakes, and often cover many miles to find suitable seasonal habitat. The habitats smallmouths choose each season seem to have been determined thousands of years ago, as bass return to the same areas to spawn, summer, and winter every year in most environments.

“In northeastern Wisconsin, adult smallmouth bass left the Wolf River to spawn in the smaller Embarrass River when water temperatures reached 59°F in May,” the study continued. “They moved as much as 45 miles upstream in the Embarrass River and remained there for the entire summer.”

Other studies have revealed that much like their lake-dwelling cousins, some stream smallmouths migrate short distances between winter, spring, and summer habitats—if at all. “In some rivers, smallmouth bass did not make long-distance migrations to spawning areas and instead spawned in the same general area where they spent the rest of the year. Limited or no spawning movements were found in the Snake, Jacks Fork, and Huron.

“In our study, we observed an apparent spring spawning migration. We tracked six smallmouths during this period, five that began the spring in the Pecatonica and one in Otter Creek. Two major movement periods occurred, both associated with floods. The first period was in early May, when river flows were receding from levels three times higher than normal and minimum water temperatures were 50°F to 54°F. Two of the smallmouths moved from the Pecatonica back into Otter Creek. One fish resided for the remainder of spring and summer near where it had been initially released after radio implantation. The second movement period came during early to mid-June, when flows increased by a factor of two, and minimum water temperatures increased from 54°F to 61°F.” Among the five fish that did migrate to spawning habitat, then on to summer habitat, the average distance covered was about 4 miles and the longest distance covered was over 7 miles. Some fish moved upstream to spend the summer, some moved down.