Sea Lamprey occurs as ammocoetes in medium-sized streams near the mouths, and in areas with clean sand. The adult phase is parasitic and typically found only in the big lakes or the ocean. It has lived in 14 watersheds and is native to all of them except Erie. Anadromous life styles are still easily seen in the Delaware, Lower Hudson and Long Island watersheds but have been eliminated from Susquehanna and Chemung watersheds. Land locked (and native) populations are found in Lake Ontario, Oswego, Champlain and Saint Lawrence watersheds, and they are detrimental to sportfish management of salmonids. Large-scale control programs are underway in those tributaries of the Lake Ontario, the Finger Lakes, Lake Champlain and Lake Erie.