Alewife
Alosa pseudoharengus

 

Click on the map for an enlarged view
Distribution:
In Nebraska:  See map below
In the U.S.:  From Newfoundland to Northern South Carolina
Origin:  Eastern Coast of the U.S.

Characteristics: 

Silver in color with a black spot behind gills
Large eyes
Spawn in spring then migrate to deep water for fall and winter

Impacts:

Lower Zooplankton population
Eat eggs of other fish
Cause decline in native species
Have mass die offs that cause bad odors

Control Methods:

Can be controlled by stocking brown trout
Netting them
Use chemicals to kill all fish in water body and start over

This species was probably native to Lake Ontario and spread through the Great Lakes via the Welland Canal. The alewife was intentionally stocked in inland waters.  Alewives are known to reduce zooplankton populations and prey on salmonids.

For More Information on Alewives:
Virginia Institute of Marine Science
Vermont Dept of Water Quality
USDA on invasive species