Movement and Survival of Wild and Stocked Paddlefish Across Their Species Range: Implications for Migratory Fish Management

Migratory freshwater fish have sustained substantial declines globally due to factors such as habitat loss and overharvest. Attempts at large-scale conservation plans for these fishes have been made in the USA through the Mississippi River Interstate Cooperative Resource Association (MICRA) paddlefish and sturgeon committee. The most conspicuous result of this effort has been a long-term, nearly range-wide mark-recapture database containing >35,000 encounters with individually marked paddlefish and release information on >2 million batch marked hatchery-reared paddlefish. We used data from the paddlefish stock assessment database to describe 1.) survival and recapture probabilities of paddlefish, 2.) the spatial extent of wild and stocked paddlefish movements and 3.) concomitant management implications of these survival and movements estimates.  Annual survival probability estimates of wild paddlefish were lowest for the Mississippi River Basin (the Mississippi River and its tributaries, except the Missouri and Ohio rivers—S=0.64) and highest for the Missouri River Basin (S=0.87).  Survival, recapture and movement probability estimates for stocked paddlefish were not reliable (very wide or suspiciously small confidence estimates) likely due to a very small number of recaptures compared to the number of stocked fish at large (recaptures <1%). Paddlefish immigration to and emigration from river basins appears to play a role in population dynamics at the long-term, range-wide scale and suggests that current state-specific management of migratory fish may not be of a sufficient spatial reach to effectively manage migratory fish populations.  Movement information contained in this database may provide useful for creation of an interjurisdictional management framework.