Wetlands, Estuaries, Rivers and Coastal Waters
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)

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


List of All Pages on this Website

Others' Related Links

Chambers and Associates
9814 Kensington Parkway
Kensington Maryland 20895-3425
(T) 301-949-3003    (Fax) 301-949-3003

[email protected]
Blue Marlin Logo by Artist Ron Pittard

International Angler Ring

previous cast | random | poll | tackle | search | next cast

IAR powered by FishNation Join today