Stratégie optimale de contrôle des espèces envahissantes en vue d’assurer la survie et le rétablissement du corégone de l’Atlantique dans les lacs de la Petite Rivière

Abstract

Over three years (2014-2016), 2,362 Smallmouth Bass and 3,129 Chain Pickerel were removed from Hebb Lake by boat electrofishing and angling methods. The proportion of the total population represented by these removals is unknown as there are no estimates of total population size for either species. Boat electrofishing depletion experiments demonstrated that localized populations of both Smallmouth Bass and Chain Pickerel could be dramatically reduced using a multi-pass methodology. However, depletion methods were found to be time consuming, and permitted limited shoreline coverage. Catch per unit effort (CPUE) efficiency decreased with consecutive passes. The effect of depletion removals is assumed to be temporary, as the site is likely quickly recolonized by individuals from unfished areas adjacent to the depletion site. Boat electrofishing linear transects were applied to increase total lake shoreline coverage. Removals in this case are primarily juveniles. Angling targeted at invasive species removal was applied as a supplementary control technique. Angling generally selected for larger fish than boat electrofishing. Eradication of invasive species is considered unlikely using boat electrofishing and angling methods, however control of the population may be achievable with ongoing effort. Other studies using boat electrofishing have been successful at controlling Smallmouth Bass abundance, albeit with much higher levels of electrofishing effort applied to smaller lakes. Once mitigation effort is removed, it is expected the population would quickly rebound.