Silver Shiner Size-Class Structure, Habitat Utilization, Movement and Persistence in an Urbanized Fragment of a Great Lakes Tributary

Silver Shiners (Notropis photogenis) were monitored with underwater videography, captured and measured, and their habitat was characterized from 38 locations in an urbanized fragment of the Grand River, Ontario, from 2006 to 2015. Cobble was the most frequently used substrate type (44.6% of observations) in heterogeneous transitional habitat near backwater pools and areas adjacent to deep runs. Population size structure and qualitative growth patterns suggested rapid growth during the first 2 y after hatching (n ¼ 439). The largest fish captured was 143 mm total length, which is a new Canadian record and tied the world record from Tennessee. Spawning was not directly observed, but gamete evidence suggested it took place from early to mid-June when the water temperature was approximately 24 C. Underwater video monitoring revealed schools of Silver Shiners migrating upstream during late afternoon and evening in October/November presumably to overwintering areas. Silver Shiners were located near known sources of groundwater seepage in 92% of observations. This association requires further investigation to determine if groundwater represents critical habitat that facilitates persistence of Silver Shiner populations in urbanized rivers with notoriously poor water quality.