Alewife (Gaspereau), Alosa pseudoharengus

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Distribution:

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Description:  

The alewife has blueish-grey to olive backs with silvery glistening sides.  The body is deep and strongly laterally compressed.  The belly of the alewife narrows to a blade like ridge, which has many scutes giving it a serrated or toothed appearance.  The eye is large and the mouth up turned and terminal.  The lateral line is absent, and the large scales number 42 - 50 along the side.  There is a prominent black spot near upper rear edge of operculum.  The gill rakers number 39 - 41 on the lower limb or the first gill arch.  The caudal fin is sharply forked and the anal fin is short with a broad base. The average size is around 6 inches, but can be larger than 12 inches.  Peritoneum is pale or silvery (otolith distinctive).

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Biology:

This anadromous schooling fish is mainly a marine species returning to freshwater  only to spawn.  They prefer open water regardless of substrate type.  Alewife eat aquatic insects, plankton, and in some cases plant materials like algae.  The alewife migrates up  rivers in early spring to calm areas of the river or connecting lakes.  Spawning takes place over sandy or gravel substrate where the non-adhesive eggs are randomly scattered.  The young alewife can be seen in large numbers cruising along the shore during late summer. There is a commercial fishery for alewife mostly for the production of pet foods and a small percent is retained for human consumption.  Alewife are used as a bait fish commonly used in the lobster industry. Large fish including burbot and lake trout will eat adult alewife.  Juvenile alewife are most likely a major source of food for many fish and birds.

Similar Species:

Blueback Herring; American Shad