The Richelieu is the largest tributary on the Saint Lawrence River’s south shore. Totalling 130 km in length, it originates in Lake Champlain, crosses the Mont Saint-Hilaire Biosphere Reserve and empties into the Saint Lawrence at Sorel. Although very polluted, the Richelieu contains the greatest number of fish species of any river in Quebec. Fully 60 of the province’s 116 freshwater species can be found in its waters, including pike, walleye and bass. The river is also home to the copper redhorse, a fish found only in southern Quebec and nowhere else in the world.