Brook trout
The lower stretch of the Poplar River serves as a fishery for pink, chinook, and coho salmon in the spring, and rainbow and brook trout in the fall. The largest chinook salmon caught on record in Minnesota was taken here in 1989. from its mouth, a barrier waterfall prevents Lake Superior fish from traveling any further upstream. Brook trout can be found anywhere in the upper 17 miles of the Poplar, in increasing numbers as one moves further north. In the lower portions, spawning grounds for brook trout are limited by a recent buildup in silt, and warm water temperatures in the summer are stressful on the population. The populations of warmwater species such as smallmouth bass, pumpkinseed sunfish, and bluegill have been increasing in these regions over recent surveys. In the upper watershed of the Poplar, the smallmouth bass has spread into every major lake north of Rice Lake since being introduced into Crescent Lake in the 1990s.