Movement and Habitat Use by Mottled Sculpin After Restoration of a Sand-Dominated 1^st-Order Stream

Abstract

Anthropogenic activities have greatly altered the natural flow regime of lotic ecosystems in many ways, including dams and culverts, which restrict sediment transport and fragment fish habitat. Sculpins, Cottus spp., are an important food-web link between macroinvertebrates and larger stream fishes and are greatly affected by culverts. Results from a previous study indicate a substantial increase in the relative abundance of mottled sculpin, Cottus bairdii, was observed upstream of a renovated road-stream crossing during the first season after construction. Redistribution of this nature from a putatively sedentary species would have required substantial movement. Our objectives were to quantify post-restoration mottled sculpin movement and habitat use in a restored stream reach. The extent of post-restoration mottled sculpin movement and habitat use were directly measured using telemetry of Passive Integrated Transponder (PIT) tag-marked fish. The maximum linear distance moved by a marked mottled sculpin was 839 m; 23% of marked mottled sculpin moved >100 m. The number of detections of marked mottled sculpin in each segment was significantly correlated with the amount of small wood (5–10 cm diameter). Increased distribution of mottled sculpin in previously unavailable upstream habitats coupled with substantial post-restoration movement distances provides new insight on their potential for redistribution following habitat reconnection, which is an important consideration for stream restoration projects.