Mass removal of submerged logs triggers sharp decline of yellow perch in Wisconsin lake

A unique whole-lake study in Little Rock Lake, an 18-hectare undeveloped lake in Vilas County, Wisconsin, divided the water body with a curtain to create separate treatment and control basins. In 2002, researchers extracted roughly 70% of the coarse woody debris along the shallow shoreline of the treatment side. Within two years, the once-abundant yellow perch in that basin dwindled to near-absence, a result attributed to increased predation and a lack of successful young fish.

The untouched basin continued to produce several generations of perch each year. Largemouth bass in the treated area shifted toward terrestrial prey and exhibited slower growth compared with their counterparts in the control basin. Benthic macroinvertebrate communities, however, remained largely unchanged across both basins. The findings highlight the critical role of submerged logs in supporting fish populations and suggest that shoreline development that removes such structures could harm fisheries.