Alewife

Common Name (s): Alewife

Scientific Name: Alosa pseudoharengus

Common Information: An Alewife is an anadromous species of herring found in North America. During their egg stage, they live off of the nutrients provided to them. And although little is known about the predators of the eggs, the life of an Alewife is very dangerous. One female Alewife can produce somewhere between 60,000 to 100,000 eggs, but only a few eggs survive to the juvenile stage, and sometimes only as few as three juveniles survive to adulthood.

The macrohabitat of Alewife eggs are ponds and lakes or the quiet backwaters of rivers and streams. The water must be lentic, which means slow or motionless water. Water temperature should be around 51℉ and the water depth around 150-300mm. Substrate sand or gravel is best for the eggs. Once laid they receive no further parental care. If an Alewife reaches the juvenile stage their diet changes and they consume mainly zooplankton. Their predators become burbot, lake trout, eels, bass, walleye, and whitefish.

Alewife serves as food for larger organisms, including Atlantic salmon and lake trout. Herons and other birds, as well as otter, mink, and other aquatic mammals, are all Alewife predators. In addition, humans have fished for alewives for centuries, as they were abundant and could be easily preserved well with salt or smoke. Even today, they are a popular choice for bait in the lobster fishery.

The habitat of an adult Alewife can adjust to a wide range of salinities but they may prefer cooler water than other anadromous fish. Every May and June, adult alewives, guided by their sense of smell, migrate upstream from the ocean to rivers, streams, ponds, and lakes to spawn. Spawning occurs in ponds and lakes or the quiet backwaters of rivers and streams. Some males return to freshwater when they are three years old. Alewives run first and begin spawning when water temperatures are 51°F followed by bluebacks, which begin spawning when water temperatures reach 57°F. Spawning is very stressful and makes them vulnerable to being eaten.

The conservation status of an Alewife is secure and they are not on any endangered species lists. But their habitat is at risk due to the overwhelming amount of dams that have been restricting their access to breeding habitats. In order to return to the Megunticook to spawn, Alewife must have an easy path to follow. Multiple dams stand in the way of a safe breeding ground for the Alewife In order to have a safe and successful breeding trip, the dams must be removed or fish ladders must be installed. These will allow the Alewife to safely make their way upstream and lay their eggs.