Spawning Abrasion Patches in Female Bighead and Silver Carps as Indicators of Spawning Activity

Authors:

•       Goszewski, Thomas P. University of Missouri-Columbia. Undergraduate; (636) 734-9148; tpgyt7@mail.missouri.edu
•       Chapman, Duane C. USGS Columbia Environmental Research Center; (573) 289-0625; dchapman@usgs.gov
•       Noltie, Douglas B. University of Missouri-Columbia; (573) 882-9421; NoltieD@missouri.edu

Abstract:

Female bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix (together, bigheaded carps) exhibit an irritated patch during the spawning season.  The irritated patch is located halfway between the pelvic and pectoral fins on the fish’s ventral margin, and apparently results from abrasion caused by males rubbing their pectoral fins under the female.  Summer-caught fish with these abrasions were always female.  These irritated patches of bigheaded carps have not been previously described in the scientific literature.  We evaluated the presence of regenerated scales in the area of the patch, as an indicator of previous spawning activity by winter-caught fish.  Such an indicator could be useful to determine the age and length at onset of maturity.  Also, if a female fish is captured from a body of water thought not to contain a population of bigheaded carps (such as the Laurentian Great Lakes) it could be used to determine if male fish are also present and attempting to spawn.