Seasonal Distributions, Characteristics, and Population Dynamics of Shovelnose Sturgeon in the Lower Platte River, NE

Declines in shovelnose sturgeon Scaphirhynchus platorynchus abundance have been observed throughout their native range for the past 100 years.  These declines are accredited to anthropogenic disturbances associated with habitat alteration (e.g., dams), agricultural use (e.g., irrigation), and overharvest.  This decline is also thought to be occurring in the Platte River, NE where this species is both recreationally and ecologically important to the state.  However, little information is available on the current status of the species in this system.  Therefore, our objective was to determine the current shovelnose sturgeon abundance, distribution, and population dynamics within the Lower Platte River.  We collected shovelnose sturgeon using trotlines and trammel nets over three seasons: spring, summer, and fall during 2009-2010.  Our results show that the abundance of shovelnose sturgeon is higher (1.40 fish/100m ± 0.22; 1.04 fish/20 hook-nights ± 0.12) than the lower 54.0 km of the river compared to reaches upstream (0.27 fish/100m ± 0.06; 0.21 fish/20 hook-nights ± 0.06).  Shovelnose sturgeon abundances were highest in spring (1.23 fish/20 hook-nights ± 0.20) and lowest in summer (0.28 fish/20 hook-nights ± 0.07) indicating possible associations with hydrological patterns for the river. Preliminary movement results indicate a residential and transient population using the Lower Platte River.  This study will provide the information needed to appropriately make management decisions concerning shovelnose sturgeon and help provide information needed to better understand the range-wide decline of the species.