Alewives are critical to the ecology of freshwater, estuarine, and marine environments. They provide an alternative prey item for osprey, eagles, great blue heron, loons and other fish eating birds at the same time juvenile Atlantic salmon are migrating downriver. Alewives provide cover for upstream migrating adult salmon that may be preyed on by eagles or osprey, and for young salmon in the estuaries and open ocean that might be captured by seals. It is important to understand that alewives tie our ocean, rivers and lakes together, providing vital nutrients and forage needed to make healthy watersheds. Between and within those various habitats,everything eats alewives: striped bass, bluefish, tuna, cod, haddock, halibut, American eel, brook trout, rainbow trout, brown trout, lake trout, landlocked salmon, smallmouth bass, largemouth bass, pickerel, pike, white and yellow perch, seabirds, bald eagle, osprey, great blue heron, gulls, terns, cormorants, seals, whales, otter, mink, fox, raccoon, skunk, weasel, fisher, and turtles.

 http://www.maine.gov/dmr/searunfish/alewife/

Each year on the Sebasticook the anadromous alewife undertakes a remarkable journey, beginning when it first wriggles out of a waterborne egg alongside tens of thousands of siblings. It heads downstream, past Benton, seeking the Atlantic Ocean, and then heads down the coast, sometimes traveling as far as South Carolina.

For three years, the alewife stays at sea, swimming thousands of miles while evading predators up and down the coast.

At age 4, instinct drives them to head back upriver to spawn with each inch of the 65-mile trip a hard fought battle against the current, won at a rate of about one mile per hour.

If 100,000 fish make it back to spawn in the Sebasticook, they can lay 15 billion eggs, but  predicting the number of alewives that will successfully complete the cycle of life in any given year is impossible.

Nate Gray, Fisheries Biologist with the Maine Department of Marine 
Resources.

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