Black Bass Diversity: Multidisciplinary Science for Conservation

Risk of Population Decline for Largemouth Bass in a Potomac River Fishery (USA): Effects from Invasive Northern Snakehead

Joseph W. Love, Joshua J. Newhard, and Mary Groves

doi: https://doi.org/10.47886/9781934874400.ch19

Abstract.—Conservation of Largemouth Bass (LMB) Micropterus salmoides populations requires an understanding of population dynamics that are influenced by environmental challenges, such as the spread of invasive species. We used an age-structured population model to compare population growth rates (λ) between a simulated population that included invasive Northern Snakehead (NSH) Channa argus as a competitor and predator and a simulated population that did not. We then assessed the sensitivity of our results to natural variation in LMB recruitment. When recruitment of LMB was already poor, there was a high risk of population decline that did not depend on whether NSH was included in the model scenario. When recruitment of LMB was high, the risk of population decline was only 40% when NSH was not included in the model scenario; however, predation by and competition with NSH caused a higher risk of LMB population decline. Regardless of the level of LMB recruitment, the size of the LMB population at equilibrium was 20% lower (on average) when including NSH in the model. We conclude that when habitat conditions do not already significantly limit recruitment, populations of LMB may be adversely affected by cohabitation with NSH. Preventing the spread of NSH will lessen ecosystem pressures that negatively affect the LMB population. We encourage continued vigilance in conserving LMB populations by encouraging actions that promote recruitment and prevent spread of invasive species.