Using Pectoral Fin Ridges to Assign Sex to Bighead Carp

Bighead Carp Hypophthalmichthys nobilis are native to eastern Asia, have been introduced throughout the world, and are subjected to immense management where they persist. Identifying the sex of Bighead Carp during monitoring efforts could provide additional data to enhance fishery management schemes, thereby facilitating better management. We assessed the presence (male) or absence (female) of bony ctenoid serrations on the upper edge of the foremost pectoral fin ray to noninvasively and nonlethally determine the sex of 745 Bighead Carp collected from March to December. Bighead Carp sex was correctly assigned 93% of the time by three readers, with males correctly identified 94% of the time and females 92% of the time. A generalized linear model indicated that total length and water temperature influence the success of sex assignment. Overall effects of water temperature and size were relatively low, as the pectoral fin method was highly accurate (93%) and precise (88% agreement among readers). Thus, the pectoral fin method provides reliable Bighead Carp sex assignment that can be used on wild-caught fish to noninvasively and rapidly assign sex in the field or lab.