 Smallmouth bass were often introduced to northern rivers now too warm for native trout, and slowly became a popular gamefish with many anglers.Equally adaptable to large, cool-water impoundments and reservoirs, the smallmouth also spread far beyond its original native range.Later, smallmouth populations also began to decline after years of damage caused by overdevelopment and industrial and agricultural pollution, as well as a loss of river habitat caused by damming many formerly wild rivers in order to form lakes or reservoirs.