Predatory impacts of invasive Blue Catfish in an Atlantic coast estuary

Abstract

Objective Predatory invasive fishes may consume species of management interest and alter food webs. Blue Catfish Ictalurus furcatus is a large-bodied, salinity-tolerant species that exhibits broad diet breadth and preys on species of both conservation concern and fisheries management interest. To better understand the ecological consequences of the establishment of Blue Catfish fisheries, estimates of predatory impacts are needed. Methods Using a Monte Carlo simulation, we integrated abundance estimates, diet information, and consumption-to-biomass ratios to estimate population-level Blue Catfish predation for a large Chesapeake Bay tributary along the mid-Atlantic coast of the United States, the James River. Result Population-level annual predation estimates by Blue Catfish exceeded 100 metric tons for several species or taxa of interest, including an estimated 400.7 metric tons (95% CI = 272.6–613.2) of blue crab Callinectes sapidus . Prey species abundances were unknown and thus limited opportunities to evaluate prey population responses. For instance, effects of Blue Catfish on blue crab populations remain unknown without tributary-specific estimates of blue crab abundance, but comparisons to landings data suggests that Blue Catfish predation on blue crab in the James River may be low compared with harvest. Conclusion Estimation of Blue Catfish predatory effects may inform development of management goals and objectives that balance diverse stakeholder interests. This work provides beneficial information to assess trade-offs of Blue Catfish fisheries and their effects on coastal aquatic resources.