Salmon River Atlantic salmon populations declined rapidly in the mid-19th century due to overfishing, pollution, and the construction of numerous dams preventing access to spawning grounds. By 1872, these native salmon were extirpated from the river. Between 1873 and 1898, approximately 1.1 million Chinook salmon were stocked in the Salmon River; however stocking ceased once it was demonstrated that no natural reproduction of these salmon was taking place. This same period of time saw the stocking of 144,000 Atlantic salmon fry, however poor survival of these fish led to this program being discontinued as well. By 1898, all salmon in Lake Ontario were apparently extirpated.