Anthropogenic Obstructions to Paddlefish Movement and Migration

Abstract

Paddlefish Polyodon spathula are behaviorally, morphologically, and physiologically adapted for prolonged free-swimming at moderately high speeds but not for maneuverability which makes them prone to impacts from submerged structures. These structures include low-head dams, weirs, dikes, levees, high-head dams, dredges, diversions, intakes, and vessels. Impacts include blocked migrations, reduced access and quality of habitat, entrainment, impingement, trauma, and stranding. Effects of these impacts on individuals are displacement, injuries, and death; effects on populations are fragmentation, lower gene flow, lower reproductive success, and elevated rate of mortality. Despite this, the status of the Paddlefish in most parts of its historic range is secure. Management techniques, like stocking and habitat restoration, are typically implemented at the local level but appear effective at conserving the species range wide. Refinement of management techniques, however, is still possible by modifying operations of structures and by rescuing stranded Paddlefish.