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Coastal Resource Inventory Tutorial

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7. Learn More About Migratory Fish Runs

What is it?
Anadromous fish spend most of their adult lives in salt water and migrate to freshwater rivers and lakes to reproduce. After the eggs hatch, the young fish spend varying lengths of time in freshwater before migrating to saltwater where they mature. The fish eventually return to freshwater to spawn. Only one percent of all fish in the world are anadromous; these fish undergo physiological changes that allow them to survive as they move between fresh and salt water. On the east coast anadromous fish include river herring (American shad, alewife and blueback herring), striped bass, Atlantic salmon and shortnose sturgeon.

Species: Alewife and Blueback Herring
Although similar in appearance, the alewife (Alosa pseudoharengus) has a larger eye, is gray-green and is usually longer than the blueback herring (Alosa aestivalis). The blueback herring is blue-grey. Both fish have a prominent dark shoulder spot, and the females are larger and heavier than the males.


Alewife (ocean-run) (Alosa pseudoharengus)


Blueback herring (Alosa aestivalis)


Why are they important?
Both of these fish are important to the aquatic food chain; they are preyed upon by other fish, as well as provide food for birds and other animals. In addition, a single female may produce up to 200,000 eggs, only a few of which survive to maturity; the rest become food for other species.


Photo: Upper Millpond Dam Fishway (dry), Old Lyme, Connecticut: Courtesy of Old Lyme Conservation Trust

 

Metadata
Anadromous Fish Runs
Tidal Wetlands
CT DEP data layers

 

Links
NOAA Fisheries' Office of Habitat Conservation, the Habitat Protection Division - Visit the Anadromous Fish and Essential Fish Habitats sections.
The American Sportfishing Association
National Marine Fisheries Service Office of Protected Resources
United States Fish and Wildlife Service

 

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 Migratory Fish Legend
 

Watershed Basins

Town

Migratory Fish Runs

Tidal Wetlands

Water Features

 

 Migratory Fish Larger View

 

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