Assessing Efficacy of Pectoral Fin Sexual Dimorphism for Determining Gender of Bighead Carp [poster]

Understanding population characteristics (e.g., sex composition) of Bighead Carp Hypophthalmichthys nobilis, an invasive species expanding throughout the Mississippi River Basin, can help agencies better manage invaded systems. Morphological differences, such as pronounced pectoral fin ridges of Silver Carp H. molitrix, can quickly and accurately determine gender. However, this gender determination technique has not been validated for Bighead Carp, a relative of Silver Carp. The objective of this study was to assess the utility of using the presence or absence of pronounced pectoral fin ridges to determine Bighead Carp gender. Bighead Carp were collected in the upper Illinois River via contracted commercial gill/trammel netting from May to December 2017. Gender was assigned using the presence or absence of pronounced pectoral fin ridges and then verified by gonadal investigation. Overall, classification success rate was 80%, with greater success classifying females (89%) than males (70%), although a significant difference was detected between pectoral fin identification and gonadal identification (χ2 13 = 9.3, df = 1, P = 0.002). After surpassing the learning curve and whether or not an expected level of error can be tolerated, the pectoral fin gender assignment technique could be consider for determining sex ratios of Bighead Carp populations.