Bighead Carp Hypothalmichthys nobilis and Silver Carp Hypothalmichthys moltrix (hereafter collectively referred to as Bigheaded Carp) have spread throughout the majority of the Mississippi River since the 1970s. The current northern invasion edge of Bigheaded Carp in the Upper Mississippi River spans between pools 14-20 due to limited passage at Lock and Dam 19. Mechanisms limiting adult Bigheaded Carp abundance above Lock and Dam 19 are unknown, but may be due in part to lack of reproductive success influenced by adult abundance and environmental factors. Our objective was to investigate how relative adult biomass and river temperature and discharge affect maximum annual Bigheaded Carp larval production in the Upper Mississippi River using a Ricker stock-recruitment model. Adult Bigheaded Carp relative biomass (kg/hr) was estimated annually with boat electrofishing and larvae were collected every 10 d between May and August 2014-2017 in pools 14-20 in the Upper Mississippi River. Adult relative biomass ranged from 0.0 to 880.9 kg/hr whereas maximum annual larval densities ranged from 0.0 to 2,869.4 larvae/m3. After accounting for variability among pools and years, the most supported linear Ricker stock-recruitment model indicated the number of recruits per spawner decreased with increasing adult relative biomass and increased with mean discharge. Our results highlight the importance of adult biomass and river discharge conditions for reproduction of Bigheaded Carp along leading edges of invasion. Management strategies that aim to maintain low adult abundance where reproduction is not yet occurring could help limit population increases via reproduction whereas reducing high adult biomass (e.g., commercial harvest, barriers) may result in greater Bigheaded Carp reproductive output in the Upper Mississippi River.

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