Mortality of Paddlefish in Hoop Nets in the Lower Missouri River, Missouri

Abstract Mortality of paddlefish Polyodon spathula collected in hoop nets was observed in the lower Missouri River, Missouri, in 1997. Unbaited hoop nets of three mesh sizes (2.5, 5.0, and 7.5-cm, bar measure) were fished from Mar to Oct in two habitats (inside-bend steep-cut banks and outside-bend revetted banks). In 462 net-days of effort we caught 23 paddlefish in 5.0- and 7.5-cm-mesh nets but none in the 2.5-cm-mesh nets; 35% of the paddlefish collected were found dead. Most paddlefish (90%) were collected along outside-bend revetted banks in May, Jun, and Jul. Mortality was not associated with water temperature; however, 80% of paddlefish collected from May through Jul in 7.5-cm-mesh nets were dead versus 21% in 5.0-cm-mesh nets. We estimated that one paddlefish would be killed for every 37 net-days of effort, based on random placement of hoop nets within macrohabitats. Our data indicate that bycatch mortality of paddlefish in hoop nets should be considered and evaluated further in the lower Missouri...