Quantification of Daily Otolith Increments in Young of Year Asian Carp

Silver and bighead carp are invasive species established throughout the Mississippi River Basin. Many studies and resources have been dedicated to their management.  However, information on hydrological spawning triggers and growth of juvenile Asian carp is still lacking. Here, daily incremental growth annuli from otoliths are used to estimate birth and growth of young of year Asian carp. We collected juvenile Asian carp from the LaGrange Reach of the Illinois River following a spawning event in August 2014. Total length was measured, and the otoliths removed from each individual. A small piece of caudal fin tissue was excised for genetic analysis. Otoliths were aged from up to 20 fish per 5 mm length group (15-79 mm). The extracted otoliths were mounted to slides, polished, photographed, and aged. Otolith microstructure was validated using juvenile Asian carp from Chinese aquaculture. Preliminary results show the collected Asian carp range from 26 to 45 days old, placing their birthdays between June 22 and July 11, 2014. Further study of age will help determine spawning periodicity and hydrological spawning triggers. Ultimately, the ability to determine daily growth rates of young of year Asian carp will help in the management of these invasive species.