Phenotypic plasticity in life-history characteristics of invasive blue catfish, Ictalurus furcatus.
Blue catfish, Ictalurus furcatus, are an invasive species in the Chesapeake Bay region, where they negatively impact native species of ecological, economic and cultural value. Management of blue catfish is, however, hindered by a lack of information on their population dynamics. We studied decadal changes in growth and body condition and made inferences about maturity schedules of blue catfish in two Chesapeake Bay subestuaries (James and York rivers). Specifically, we quantified the dynamic responses of these populations to biotic and abiotic characteristics experienced by fish during two stages of invasion (1998-2000 or "early" period and 2015-2017 or "recent" period). In general, somatic growth rate, body condition and reproductive allocation were greater in the early, less dense populations, which also exhibited larger mean size-at-maturity. We observed sexual dimorphism in growth patterns where males reached larger asymptotic sizes than females in both rivers. Such sex-specific and density-dependent responses in life-history characteristics provide information critical for the development of quantitative models and deployment of effective management plans. Our results highlight the need for management plans to consider dynamic feedback mechanisms: efforts to decrease population density may diminish the negative impacts of blue catfish on native species, but this will be offset by increased growth rates and higher reproductive output.