Alewife
Alosa pseudoharengus
Alewife are a species of river herring with a larger eye and less elongated body than their close relative, the blueback herring. (Photo courtesy Virginia Institute of Marine Science) For use contact the Virginia Institute of Marine Science (VIMS)
Alewife herring gather after swimming upstream to spawn in Susquehanna State Park in Harford County, Md., on April 20, 2017. (Photo by Will Parson/Chesapeake Bay Program)
A “forage fish,” the alewife has a number of predators, including fish-eating birds like the osprey and double-crested cormorant. (Dave Maher/Flickr)
Also known as the big-eye or branch herring, the alewife is a thin, silver fish with a single dark shoulder spot located behind its head.
Appearance
The alewife is a thin, silver fish with grayish-green back, smooth scales and large eyes. A single dark shoulder spot located behind the head appears on fish greater than 3.9 inches long. Adults grow to 15 inches and weigh less than one pound. Females are bigger than males.
Feeding
Schools feed in mid-water or near the surface on zooplankton, shrimp, small crustaceans, small fish, fish eggs.
Predators
A “forage fish,” the alewife has a number of predators, including lake trout, eels, bass, walleye, whitefish and salmon, as well as fish-eating birds like the osprey and double-crested cormorant
Reproduction and Life Cycle
An anadromous fish, the alewife must migrate from the ocean into freshwater rivers, streams and ponds to spawn each spring. Females reach spawning grounds first. Older fish are the first to spawn; adults move downstream after spawning takes place. Eggs are adhesive when first laid, but soon lose stickiness and settle on substrate. Eggs hatch in three to six days. Young grow rapidly through spring and summer. While some will spend first winter in the Bay, most gradually migrate downstream before entering the ocean in the fall. Less than one percent will survive spawning season. The oldest fish recorded at spawning sites were 9 to 10 years old.
Did You Know?
- Alewives are packaged fresh, smoked, salted or pickled for human consumption. Alewives are also used for pet food, lobster and snow crab bait and processing into fishmeal and fish oil.
- The "river herring" fishery (which includes the alewife and the blueback herring) has been one of the most valuable in the Bay, with annual catches once exceeding 8 million pounds in Maryland and 30 million pounds in Virginia. The degradation and destruction of spawning habitat and the restriction of spawning migration (or fish passage) by dams have contributed to the decline of these stocks.
Sources and Additional Information
- Life in the Chesapeake Bay by Alice Jane Lippson and Robert L. Lippson
- Fishes of Chesapeake Bay by Edward O. Murdy, Ray S. Birdsong and John A. Musick
- Alosa pseudoharengus – University of Michigan Museum of Zoology
- Alewife and Blueback Herring – Maryland Department of Natural Resources
- Alewife (Alosa pseudoharengus) – Virginia Department of Game and Inland Fisheries
Quick Facts
Species
Native
-
Size
15 inches in length; weigh less than one pound -
Habitat
Spends most of its time in coastal waters when not migrating into freshwater to spawn
-
Range
Native to the Atlantic Ocean and the rivers and streams that drain into it from Newfoundland to North Carolina; Great Lakes and Finger Lakes contain landlocked populations. Adults enter the Chesapeake Bay and its tributaries in spring to spawn.
-
Diet
Feeds on zooplankton, shrimp, small crustaceans, small fish, fish eggs -
Lifespan
Up to 10 years -
Status
Stable
