Event Title

Effects of dam removal and habitat restoration on migratory fishes of Green Bay with emphasis on Northern Pike (Esox lucius)

Mentor 1

Patrick Forsythe

Location

Union Wisconsin Room

Start Date

24-4-2015 10:30 AM

End Date

24-4-2015 11:45 AM

Description

The removal of small stream barriers including perched culverts and low-head dams can have unique impacts on aquatic ecosystems. Opportunities to quantify these impacts are increasing throughout the Great Lakes basin. For example, two low-head dams on Duck Creek (west shore tributary of Green Bay, Wisconsin) were removed during the spring and summer of 2012. The dams were installed in the mid-1900s, and removal has opened several stream miles of potential spawning habitat for migratory fishes. However, the rapid conversion of riparian and stream habitat in the Duck Creek watershed to agricultural fields or urbanized areas leaves the overall impact of barrier removal in question. The objectives of this study included: 1) determining how fish species composition, abundance, and habitat use change in the first 3 years after barrier removal, 2) estimating migratory species recruitment after barrier removal and compare to pre-removal conditions and 3) comparing northern pike recruitment success between tributary and restored habitats that encompass agricultural ditches and wetlands. To meet these objectives, we used standard larval box traps to quantify the total number and body size of larval fish out-migrating from Duck Creek (downstream and upstream of the dam removal site), as well as several reference streams and ditches with direct connection to Green Bay (13 sites in total). Larval fish captured were counted daily, measured to the nearest mm, and released. Stream temperature and river discharge were also monitored at several locations. During the first two years of this study, several migratory fishes including white sucker (Catostomus commersoni) and walleye (Sander vitreus) were observed spawning upstream of the dam removal site and out-migrating larval white sucker were captured. Further, more than 30 fish species were identified within the box traps, including yellow perch, shortnose gar, and banded killifish, a WI species of concern. However, no larval northern pike were captured upstream of the dam removal site as expected given the increase in river connectivity. In contrast, northern pike larvae were observed at nearly all reference locations and larvae showed steady (but significantly different) growth rates throughout the out-migration period. This research suggests while the dam removal can have a positive effect on the fish community, some migratory fish may not realize the added benefit without concurrent habitat restoration.

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Apr 24th, 10:30 AM Apr 24th, 11:45 AM

Effects of dam removal and habitat restoration on migratory fishes of Green Bay with emphasis on Northern Pike (Esox lucius)

Union Wisconsin Room

The removal of small stream barriers including perched culverts and low-head dams can have unique impacts on aquatic ecosystems. Opportunities to quantify these impacts are increasing throughout the Great Lakes basin. For example, two low-head dams on Duck Creek (west shore tributary of Green Bay, Wisconsin) were removed during the spring and summer of 2012. The dams were installed in the mid-1900s, and removal has opened several stream miles of potential spawning habitat for migratory fishes. However, the rapid conversion of riparian and stream habitat in the Duck Creek watershed to agricultural fields or urbanized areas leaves the overall impact of barrier removal in question. The objectives of this study included: 1) determining how fish species composition, abundance, and habitat use change in the first 3 years after barrier removal, 2) estimating migratory species recruitment after barrier removal and compare to pre-removal conditions and 3) comparing northern pike recruitment success between tributary and restored habitats that encompass agricultural ditches and wetlands. To meet these objectives, we used standard larval box traps to quantify the total number and body size of larval fish out-migrating from Duck Creek (downstream and upstream of the dam removal site), as well as several reference streams and ditches with direct connection to Green Bay (13 sites in total). Larval fish captured were counted daily, measured to the nearest mm, and released. Stream temperature and river discharge were also monitored at several locations. During the first two years of this study, several migratory fishes including white sucker (Catostomus commersoni) and walleye (Sander vitreus) were observed spawning upstream of the dam removal site and out-migrating larval white sucker were captured. Further, more than 30 fish species were identified within the box traps, including yellow perch, shortnose gar, and banded killifish, a WI species of concern. However, no larval northern pike were captured upstream of the dam removal site as expected given the increase in river connectivity. In contrast, northern pike larvae were observed at nearly all reference locations and larvae showed steady (but significantly different) growth rates throughout the out-migration period. This research suggests while the dam removal can have a positive effect on the fish community, some migratory fish may not realize the added benefit without concurrent habitat restoration.