Seasonal movements of adult Gizzard Shad Dorosoma cepedianum in a Missouri River reservoir

Gizzard Shad Dorosoma cepedianum are important for nutrient cycling and can affect water clarity, plankton densities, and fish production levels. Gizzard Shad can also be crucial prey fish for recreationally important species such as Walleye Sander vitreus and Smallmouth Bass Micropterus dolomieu. Lake Sharpe, a mainstem Missouri River reservoir located in central South Dakota, supports a recreationally important Walleye and Smallmouth Bass fishery with Gizzard Shad being the primary prey fish. Previous work suggested Hipple Lake, a backwater embayment of Lake Sharpe, may be an important overwinter location for Gizzard Shad; however, movement of Gizzard Shad between Lake Sharpe and Hipple Lake is unknown. To understand movement of Gizzard Shad, 40 adults (20 in 2014 and 20 in 2015) were implanted with acoustic telemetry tags. Passive receivers determined movement patterns and fish locations. Analysis included 28 individuals due to removal of mortalities and other restrictions. Tagged individuals were at large in Lake Sharpe from May 5, 2014 through April 11, 2017. Over 50% of tagged Gizzard Shad overwintered in Hipple Lake. Gizzard Shad moved larger distances in the summer (average 1.5 rkm/day) and fall (average 1.75 rkm/day) months but did not move substantially during winter (average 0.42 rkm/day) and spring (average 0.37 rkm/day) months. Overall, Hipple Lake appears to be an important habitat for Gizzard Shad within Lake Sharpe and should be prioritized for habitat conservation as connectivity between Hipple Lake and Lake Sharpe is being lost through siltation and emergent vegetation growth.