A varied fauna and flora exists along the Yamaska, reflecting the various regions it traverses; species of birds, fish, amphibians, reptiles, mammals, crustaceans, insect, fungi, lichen, algae and many more populate its waters, banks, and surrounding marshes. Pollution has greatly affected the nature that used to thrive in and around the river, reducing the number of species of fish from 70 to 33 between 1963 and 2003; to counter this the Quebec government proceeds to implement fish in the river to increase fishing as a sport.