NASCO ~ The North Atlantic Salmon Conservation Organization

North Atlantic Salmon Conservation Organization
Conserving and restoring wild Atlantic salmon

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Habitat Impacts

Habitat Impact	Activities Causing Impacts
Physical
Increasing Siltation/Sedimentation	Road and railroad building, forestry, agriculture, gravel mining, channelization, in-river engineering, development, reductions in vegetation, snow removal, dams, bridges, culverts.
Blocking Migration Injury to fish, impaired access to spawning habitat and production areas, impaired outmigration to marine environment	Man-made dams, culverts, beaver and debris dams, bridges, weirs, turbines, screens.
Changing Shelter/Cover	Removal of riparian vegetation, substrate alteration, removal of in-river vegetation.
Changing Substrate	Gravel mining, channelization, sedimentation, flow modifications.
Changing River Morphology	Channelization, in-river engineering, dams, diversions.
Changing Water Quantity Alteration of flow regimes, transfers, modifications to natural/seasonal fluctuations, reduction in volume Changes in water temperature	Irrigation (direct withdrawal, wells), diversions, withdrawals, impoundments, deforestation, dams, roads (hard surfaces), cooling water intakes, dredging. Deforestation, water diversion, discharges from dams/processing plants, removal of riparian vegetation, impoundments and flow modifications from dams.
Chemical
Changing Water Quality Addition of chemicals Nutrient enrichment	Acid deposition, cultivation, pesticides, herbicides, insecticides from agriculture and forestry, run-off from hard surfaces, industrial discharges, aquaculture, atmospheric deposition Clearcutting, cultivation, fertilization, sewage processing, livestock, aquaculture.
Biological
Introduction of Diseases and Parasites	Aquaculture, transfer of fish, ballast water, transfer of water.
Changing Species/Composition/Abundance Increase in predators and competitors or reduction in prey	Stocking (introduction or augmentation), straying, harvest management.
Changing Food Supply	Pollutants, siltation, removal of riparian vegetation.