Spawning, Early Life Stage Dispersal, and Recruitment Deficiency of Wild Pallid Sturgeon in the Fragmented Upper Missouri River Basin

A reproductively functional stock of 125 wild Pallid Sturgeon Scaphirhynchus albus persists in the upper Missouri and Yellowstone rivers of Montana and North Dakota.  Successful spawning has been documented over several years, and emergence of free embryos from spawning patches has been verified to indicate functionality of reproductive processes; however, the wild stock persists in a state of severe recruitment deficiency or complete recruitment failure as young fish from natural spawning events have not been detected for decades.  It is hypothesized that multiple stressors including river fragmentation from dams and reservoirs, and flow and thermal alterations of mainstem environments disrupt Pallid Sturgeon reproductive processes to diminish recruitment success in the upper Missouri River basin.  This presentation will summarize the state-of-science for Pallid Sturgeon reproductive ecology in the upper Missouri and Yellowstone rivers, and decipher hypothesized anthropogenic impacts affecting spawning potential, early life stage survival, and recruitment in this recruitment-deficient stock.