These include habitat reme-diation, upstream and downstream passage, and competition with exotic species. Many of the historic salmon streams have degraded habitat. Salmon spawn and rear only in cool, clear water with gravel bottoms. Ongoing and future efforts to improve water quality by eliminating pollution sources and restoring riparian shelter will increase the available habitat for salmon. Because of the migratory nature of salmon, passage both upstream and downstream is an important issue.
Dams block upstream migration, preventing adults from reaching spawning areas.
If upstream spawning habitat is identified, Atlantic salmon restoration will have to consider effective means of providing both upstream and downstream passage in rivers containing dams. Introduced fish such as Pacific salmon and rainbow trout may compete for necessary resources with Atlantic salmon in both the stream and lake environment. Brown trout, another introduced species favored for the angling opportunities it provides, coexist with Atlantic salmon in Europe, and will probably have little effect on salmon restoration in New York. Control of the sea lamprey, a parasitic fish, must continue if the Lake Ontario salmon fishery is to remain healthy. The Ontario Ministry of Natural Resources began a stocking program in 1987.