Assessing Blue Catfish population dynamics across varying introduction timelines in Georgia

Abstract Objective Understanding the dynamic rate functions of introduced fish populations is essential in guiding management strategies. Blue Catfish Ictalurus furcatus population dynamics have been well studied; however, there is a gap in knowledge from populations that have been introduced into novel systems. Methods Blue Catfish were collected from the Altamaha, Ocmulgee, Oconee, and Satilla rivers in Georgia. Age estimates were obtained through otolith analysis. Multimodel growth analysis was used to describe growth patterns, and early life growth was modeled with linear regression. Instantaneous mortality of each population was estimated and compared by using a generalized linear model approach. Result The four introduced Blue Catfish populations exhibited rapid growth and low mortality rates during establishment; however, we found that populations with earlier introduction histories generally had slower growth rates and lower mortality. The Satilla River population is comparatively the most recently introduced population (first discovered in 2011) that exhibited the fastest growth and highest mortality. Conclusion Our results suggest that Blue Catfish in our study systems are in an intermediate stage of invasion and have not yet reached an equilibrium state. As density continues to increase in these river systems, we expect a decline in growth rates, delayed sexual maturation, and a greater observed maximum age. However, additional monitoring is needed to identify how population dynamics and reproductive characteristics vary over time.