ESSENTIAL FISH HABITAT
Wetlands, Estuaries, Rivers and Coastal Waters
ESSENTIAL INSHORE HABITATS ARE BEING LOST
Importance of Shallow Water Habitats to U.S. Fishery Resources

About 75% of the nation's commercially important species of marine fish and shellfish and 80-90% of recreationally important species are dependent for their survival (for spawning, nursery, migration and feeding areas) on shallow inshore waters that include bays, estuaries and rivers flowing to the sea.


Wetlands Losses


The nation has lost more than half its original wetlands to development.  Coastal wetlands provide essential habitat to thousands of species of marine fish and invertebrates, amphibians, reptiles, birds and mammals.  They also provide protection from severe storms, reduce the severity of flooding, purify water by removing sediments and nurtients, prevent erosion, and supply a major source of food (detritus) supporting fish populations on the continental shelf. 


Toxic Contaminants and Disease


As many as 20% of the bottom-dwelling fish living in our most highly urbanized estuaries (such as Boston, Norfolk, Miami, San Diego, Oakland, and Seattle) have cancerous livers and up to 70% of such fish have other types of disease leading to cancer.  These harbors' bottom sediments have high levels of polynuclear aromatic hydrocarbons (derived from burning coal and gasoline) which have been linked to such disease. 


Nutrient Loading


Nutrient over-enrichment from sewage treatment facilities and from fertilizers in stormwater runoff from farms and lawns are producing massive "dead zones" from the mouth of the Mississippi River to the Texas border and in bottom waters of Chesapeake Bay, Long Island Sound and many other bays and rivers, nation-wide.  Algal "blooms" are created.  When the algae die and sink to the bottom, their decay robs oxygen needed by fish and other marine life for survival. 


Dams and Diversions of Freshwater Flows


Rivers and streams that have been dammed (usually for hydroelectric power, navigation, or water supply) and whose flows have been diverted for irrigation of agricultural areas (often in deserts) have experienced even larger ecosystem damage than that caused by most wetlands losses and pollution, combined.  Some of the worst examples include the Everglades and Florida Bay, most of Texas' estuaries, San Francisco Bay, and the Columbia/Snake River Basin. 


Fishery Resources Declines


In the United States, most inshore-dependent species of fish and shellfish have declined in abundance by 75 to 95% of their former levels. The two primary causes, of roughly equal proportion, are overfishing and habitat loss and degradation.
Urbanization is eliminating the prime nursery areas - seagrass beds, salt marsh and mangrove habitats - near Tampa, Florida, and throughout U.S. coastal areas.
Riverine wetlands are also important habitat for marine fishery resources, which require them as essential spawning and nursery habitat.  (Photo, G. Gentry)
Shallow coastal waters like that above are important feeding and nursery areas for marine fishery resources.
Rivers and their bordering wetlands are important as  spawning and nursery areas and as migratory pathways for many marine fishery resources, some of which migrate thousands of miles at sea before returning years later to the stream of their origin to repeat the cycle.
Louisiana coastal wetlands at dusk.  (Photo, C. Lockwood)
MORE PAGES AT THIS WEBSITE

Wetlands, Estuaries, Rivers and Coastal Waters


Environmental Impact Assessment Division


Dams and Flow Diversions


Wetlands Destruction


Toxic Contaminants


Nutrient Over-Enrichment


Cumulative Effects


Importance of Shallow Water Habitats to Fish


Economic Values at Stake


References Cited
Chambers and Associates

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