Using Published Information to Predict Consumption by Northern Snakehead in Maryland

Abstract

AbstractThe Northern Snakehead Channa argus, a species originating from Asia, was illegally introduced into ponds of Maryland in 2002. Later discovered in tidal freshwater of the Potomac River, the species has become successfully established in many Maryland rivers. The magnitude of impact on preferred prey of Northern Snakehead in North American ecosystems has not been widely studied, leaving unresolved whether there are deleterious effects owed to introduction. To add insight into potential impacts of Northern Snakeheads, we calibrated a published, temperature‐dependent maximum consumption model using field data and informed its results with diet and prey preference data to compare consumption levels among prey species. The total annual maximum consumption estimated from the model for a population of 600 Northern Snakeheads, which is an abundance approximated from published population sizes in streams of the Potomac basin, amounted to consumption of 2,189 kg of fish for the population per year. We found no evidence of strong prey preferences and partitioned this consumption to relative proportions of some fishes preyed on by Northern Snakehead as 661 kg/year of sunfishes Lepomis spp., 522 kg/year of Yellow Perch Perca flavescens, 332 kg/year of Goldfish Carassius auratus, 250 kg/year of White Perch Morone americana, and 174 kg/year of Banded Killifish Fundulus diaphanus. Some of these coastal fishes comprise important recreational and commercial fisheries. The maximum consumption estimates modeled here are greater than would be observed naturally, and whether predation affects persistence of the prey species in the ecosystem will depend upon the resiliency of the prey population and its current population size, which are unknown. We conclude that, as indicated by earlier risk assessments, the Northern Snakehead is an important predator in Maryland ecosystems because it is opportunistic and is capable of consuming significant biomasses of several recreationally and commercially important fish species.