Data supporting the validation of First Annulus of Grass Carp Ctenopharyngodon idella and Silver Carp Hypophthalmichthys molitrix

A total of 83 Grass Carp and 92 Silver Carp were collected monthly from stocked ponds at Columbia Environmental Research Center. Length, weight, and collection date were recorded. The dorsal-fin rays and lapilli otoliths were collected from these specimens for the purpose of aging. An additional set of dorsal-fin rays and lapilli otoliths from Grass Carp collected in Truman Reservoir (GNIS 758286) on 20170820 and from Silver Carp collected in Mallard Lake (38.7013, -90.4949) on 20171102 were included to decrease bias. Annuli counts on all structures were completed by two experienced readers for the purpose of validating the first annulus. Two experienced readers measured all the structures collected from research ponds for the purpose of determining when annuli emerge. These results were used to determine when a fish would be considered age 1 for the purpose of this study. Measurements from the center of a structure to the edge and from the beginning of an annulus to the edge were completed. Percentage of structures aged correctly was calculated based off presence or absence of a known annulus on a structure rather than basing age off calendar date and considering fish to be age 1 after January 1. Formation of false annuli was observed consistently among both lapilli otoliths and dorsal-fin rays. The false annuli appeared to form during the capture event of the Silver Carp that were stocked into research ponds and used for this study. The presence of these false annuli effected precision of age estimates as they were frequently mis-labeled as annuli. Marginal increment analysis was utilized to validate the formation of false annuli.