Slimy sculpin (Uranidea cognata) inhabitat coldwater streams in southeastern Minnesota, USA, many of which were subjected to probable 2000-year flood events in August 2007. Floods scoured streambeds, created new stream channels, and greatly reduced benthic invertebrate communities that serve as the primary food resource for sculpin. Diets and Fulton condition of sculpin in Gilmore Creek (with moderate flooding) and Garvin Brook (with very severe flooding) had been examined just prior to flooding, and were re-examined two weeks after flooding to assess possible diet and condition changes. Diets, condition, and reproductive fitness of sculpin were examined seven months post-flood in these same two streams, plus nearby Trout run (also experienced very severe flooding). Sculpin condition declined significantly post-flood in Garvin Brook, but improved in Gilmore Creek. Prior to spring spawning, condition of Garvin Brook sculpin had improved, but Gilmore Creek fish condition worsened. Sculpin diets were more diverse before and after flooding in Gilmore Creek than in Garvin Brook, although diets of fish from both streams were dominated (>55%) by midge (Diptera: Chironomidae) larvae. Diets differed significantly before versus after flooding in the more severely flooded Garvin Brook, but not in Gilmore Creek. Prey number per sculpin stomach declined post-flood in Gilmore Creek, but not in Garvin Brook, although dry mass of prey/fish wet mass declined post-flood in both streams. Pre-spawn sculpin displayed no patterns in reproductive fitness (gonadosomatic index, hepatosomatic index, oocyte number) among the three streams that may have been related to flooding severity the previous summer. Although sculpin diets and condition were altered significantly immediately post-flood in the more severely flooded stream, food resource recovery apparently was rapid enough to prevent longer-term impacts on sculpin condition and reproductive fitness.

Toxic runoff from heavy rains on 26 September 2019 caused a complete fish kill on the 2-km-long headwater reach of Garvin Brook, Winona County, Minnesota, USA. This project examined recovery of the slimy sculpin (Uranidea cognata) population within the lower 900 m of the kill zone, comparing relative abundance estimates and size structures between the kill zone and a downstream, unimpacted reference section. Electrofishing surveys were conducted at 24 sites (12 within both kill and reference zones) at six, 11, 18, 28, and 42 months post-kill to assess relative abundance (catch-per-effort [CPE], fish/min) and population age structures (based on total length). At six months post-kill, sculpin were present throughout the kill zone. However, adult CPE declined significantly with upstream distance, suggestive of on-going immigration of adult sculpin from downstream. Age structures were similar in kill and reference zones with all size/age groups present in both zones after six months, while CPE was twice as high in the reference (6.3 fish/min) versus the kill zone (3.0 fish/min). After 11 months, CPE did not differ between zones (14 fish/min) and remained that way for the remainder of the study. However, age structures differed dramatically between zones at both 11 and 18 months post-kill; adult sculpin were significantly more abundant in the reference zone, whereas juvenile fish dominated the kill zone. By 28 months post-kill, both sculpin abundance and age structure within the kill zone had fully recovered from the kill. Sculpin recovery was accomplished mostly through enhanced reproduction within the kill zone following initial post-kill movements of both adult and juvenile fish into the kill zone from downstream. Low predation on juvenile sculpin due to reduced abundance of trout and adult sculpin post-kill likely allowed more rapid recovery of the sculpin population within the kill zone.