Will the Expansion of Northern Snakehead Negatively Affect the Fishery for Largemouth Bass in the Potomac River (Chesapeake Bay)?

Abstract

AbstractA modeling study was conducted to determine if the expansion of invasive northern snakehead Channa argus could negatively affect the largemouth bass Micropterus salmoides population size in Potomac River (Chesapeake Bay). Current distributions for both species were generated using catch records. Northern snakehead was not widely distributed during the study period and occurred mainly in upstream areas of tributaries. Many of these areas were moderately or highly suitable habitats for largemouth bass. Of sites where juvenile largemouth bass were collected, 10.6% were associated with northern snakehead. Using population modeling and measured predator–prey interactions, we determined that this level of co‐occurrence would result in a 3.8% reduction in largemouth bass population size. This prediction is consistent with current observations that indicate there has not been a negative trend in the largemouth bass fishery. As co‐occurrence was increased in the model, however, the negative impact of northern snakehead on largemouth bass monotonically increased. The time required for such increases in northern snakehead distribution is not known. If northern snakehead continues to expand its range in the absence of control measures, then our population model, with its assumptions, predicts a 35.5% reduction in the abundance of largemouth bass in the Potomac River.Received February 6, 2012; accepted June 7, 2012