Silver Carp (Hypophthalmichthys molitrix) Recruitment Sources in the Middle Mississippi River

Silver carp (Hypophthalmichthys molitrix) have spread throughout the Mississippi River Basin. In the Middle Mississippi River, Silver carp are successfully reproducing and using the associated tributaries during early life history. The relative proportion that each tributary contributes to the overall population is not fully understood. Therefore, this study aimed to identify natal environment of adult Silver carp from the Middle Mississippi River during 2015 using otolith trace element analysis. Studies have shown a strong positive relationship between water and otolith strontium:calcium ratios (Sr:Ca) for bigheaded carps. We analyzed sixty young-of-the-year Silver carp from six different tributaries and our initial results support that these ratios could be used to determine natal origins of adult Silver carp. Forty adult Silver carp otoliths from the Middle Mississippi River were analyzed using the relations developed above from young-of-the-year samples. This information will allow us to estimate the relative proportion each tributary provides to the overall population.  If a tributary contributes extensively to the adult population, management efforts should be directed at reducing reproduction potential in that location.