2 aggressive invasive fish are both living in a Maine river

BANGOR DAILY NEWS • April 6, 2026

Northern Maine has a problem. Northern pike, a voracious invasive fish that kills native species, are moving down from Canada into the St. John River and nearby bodies of water. The St. John River is already teeming with muskellunge, an invasive fish better known as muskie. In a first for Maine, the northern part of the state suddenly finds itself home to two types of aggressive invasive fish. What this might mean for the waters supporting both types of pike is a complete unknown, but it isn’t good news for any native fish remaining there, according to Maine regional biologist Frank Frost.