Spatial Ecology of Grand River Walleye; an eastern Lake Erie tributary spawning stock with barriers to access
April 2015 - January 2020
The extreme lower reaches of the Grand River, Ontario have little habitat suitable for spawning by Walleye. A low-head dam at Dunnville, 8 km upstream from the river mouth, imposes a complete barrier on most migratory fish moving upstream from Lake Erie. It is estimated that of all of the Walleye spawning habitat in the lower 42km of river (246 ha), 98% occurs upstream of this first barrier. A fishway constructed in 1995 had limited success at improving upstream access, has fallen into disrepair, and is currently assumed impassable for Walleye. A sizeable spring aggregation of Walleye (~ 15,000 in 2005) occurs downstream of the dam annually. Since 2001, efforts have been directed at assessing the aggregation and physically moving individuals past the barrier. In both 2015 and 2016, 70 Walleye from the Grand River spring aggregations were tagged as part of GLATOS project ELEWE (Spatial ecology and migration of adult Walleye in the eastern basin of Lake Erie). In each year, half were released above the Dunnville dam, and half below. Acoustic receivers are located at key locations in the lower river relative to the river mouth, the fishway, the Dunnville Dam and the next upstream barrier at Caledonia.