Otolith allometry informs age and growth of long-lived Quillback Carpiodes cyprinus

The carpsuckers, which include Quillback Carpiodes cyprinus, river carpsucker Carpiodes carpio, and highfin carpsucker Carpiodes velifer, are ictiobine catostomids (Catostomidae) native to North America. At present, the Carpiodes are classified for management purposes in a multi-species group (derogatorily labeled “rough fish”) by state agencies throughout most of their USA range. This non-specific fisheries management persists despite widespread declines among Catostomidae in North America, and as additional fishing pressures have recently evolved. Carpiodes are increasingly targeted by bowfishing with virtually no regulation, monitoring, or management. From 2018 to 2021, we analyzed the otoliths of 81 Quillback from a Minnesota population to quantify size at age, onset of sexual maturity, accrual of age spots, and recruitment dynamics. Allometric analysis revealed that otolith size increases with body mass and age at rates greater than rates for total length, scale length, and operculum length in Quillback. Our findings also indicate Quillback can possibly live at least 44 years, reach sexual maturity around ages 8–9 years, accrue black spots on epidermal tissue, similar to age-spot pigmentation in bigmouth buffalo Ictiobus cyprinellus, after 30 years, and exhibit more variable recruitment than previously documented. The life history traits of Carpiodes warrant further study for three primary reasons: the “rough fish” label has perpetuated systemic neglect, there are rising rates of exploitation, and the majority of catostomids are already classified as imperiled. Management requires updated life history data in the face of these challenges.