The fish were first spotted in August 2019 in the McKiel Brook pool of the river's southwest branch. More than 100 smallmouth bass have since been captured in an attempt to limit their spread in the river or in Lake Brook, the avenue they are believed to have used to migrate from nearby Miramichi Lake. All were between 19 and 28 centimetres long. Female smallmouth are believed to be large enough to spawn sometime after reaching 28 centimetres, or between four and five years of age. They spawn in the spring or early summer.