Since the 1970s , the rates of hybridization between the pallid and shovelnose have increased and this is attributed to changes in the Mississippi and Missouri Rivers , forcing pallid sturgeons into areas where they have a greater chance of encountering shovelnose sturgeons .
Since the 1970s , the rate of hybridization between the pallid and shovelnose has increased . 
 This is attributed to changes in the Mississippi and Missouri Rivers , forcing pallid sturgeons into areas where they have a greater chance of encountering shovelnose sturgeons .