Alosa pseudoharengus (Wilson, 1811)


The Alosa pseudoharengus or alewife is an anadromous fish that is native to the Atlantic coast of North America. It is a small herring with an iridescent green to blue to violet back. The sides are silvery with faint dark stripes. It usually has a dark spot just behind and slightly above the gills. The midline of the belly is sharp and edged like a saw. Saw belly is another common name for this fish.
Life Cycle
Alosa pseudoharengus migrate upstream from the ocean to spawn in fresh water lakes and ponds. After hatching, the young spend from about two to six months in the freshwater lake or pond, growing 1.5-5 in. (4-12.5 cm) long and then begin their migration back to the sea where they finish their maturation. It takes from 3-5 years for them to reach reproductive size. Females can produce between 48,000 - 360,000 eggs. When landlocked, this fish remains smaller, matures earlier and produces fewer eggs.
Alosa pseudoharengus have been introduced to freshwater lakes, including the Great Lakes as prey for popular game fish. They are also harvested and used as bait fish. They have spread to several other states. They are very efficient feeders on zooplankton, so in freshwater environments where they have been introduced they are successfully competing with the native species for food.
Control Efforts
Alosa pseudoharengus was introduced to freshwater lakes as prey for game fish. When appropriate, the introduction of predator fish can help control the population of Alosa pseudoharengus. A coordinated netting project may help reduce populations and constructing barriers can prevent spread to downstream to new waterways. Approved piscicides can also be used, but this is an extreme measure which will kill all fish in the lake.

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EDDMapS Distribution

EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit

Invasive Listing Sources

Taxonomic Rank

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Subclass: Neopterygii
Order: Clupeiformes
Family: Clupeidae
Genus: Alosa
Subject: Alosa pseudoharengus (Wilson, 1811)


Wildlife - Fish