Recruitment Dynamics of Channel Catfish in South Dakota Reservoirs

We quantified channel catfish recruitment (variability, synchrony, and drivers) and examined factors influencing channel catfish year-class strength in South Dakota reservoirs. Year-class strength was quantified using catch-curve residuals from six South Dakota channel catfish populations during 2011-2012.  We then modeled the effects of biotic (predator abundance) and abiotic (temperature and hydrology) factors on channel catfish year-class strength. Recruitment variability was quantified using a recruitment variability index which showed relatively consistent recruitment (0.40-0.68) among all six populations. Age frequencies indicated that western populations may be synchronous; however, correlation analysis of residuals showed no significant correlation of year class strength among any of the populations. Abiotic factors (temperature & inflows) appeared to most strongly influence recruitment. Strong year classes were produced during warmer growing seasons (growing degree days), and during years when reservoir inflow (i.e., high precipitation) was highest.  These conditions may facilitate increased spawning habitat and prey production, which may support increased production and survival of age-0 channel catfish. No direct evidence of biotic influences was found, however lack of synchony suggests biotic factors play a role in year class strength.  We saw channel catfish recruitment in South Dakota reservoirs to be consistent with landscape level factors influencing year class strength.