POPULATION DYNAMICS OF BLUE CATFISH AND EFFECTS ON BLUE CRAB ABUNDANCE IN CHESAPEAKE BAY

Abstract

Blue Catfish are a management concern in the Chesapeake Bay due their rapid expansion and predation on native species. The population-level effects of Blue Catfish predation on native species, like blue crab, and the rate of Blue Catfish population growth remain unquantified. Our objectives were to (1) quantify the relationship between Blue Catfish and blue crab and (2) estimate the Blue Catfish intrinsic rate of increase (r). We estimated the relationship between Blue Catfish relative abundance and blue crab catch using a generalized additive model and fit Blue Catfish biomass indices using a state-space logistic growth model. We estimated a negative relationship and that the current effect of Blue Catfish predation on blue crab abundance was an 8% decrease. We estimated r = 0.59/year. Current Blue Catfish harvest levels do not appear to suppress the population. Without effective control, we expect the Blue Catfish population biomass to continue to increase.