- Length: 6 inches
- Weight: 4 ounces
- Coloring: silvery with blue or blue-green metallic luster on back
- Common Names: mulhaden, grey herring, golden shad, seth, skipjack
- Found in Lakes: Michigan, Huron and Ontario (uncommon in Superior and
The alewife first arrived in Lake Superior in 1954. But tremendous numbers of these
small, silvery ocean fish never developed in Lake Superior like they did in Lakes Michigan
and Huron. Perhaps Superior's waters are too cold, or perhaps enough predator fish
survived the sea lamprey invasion there to
keep the alewife population in check.
Nonetheless, scattered populations of alewives still spawn in Lake Superior's bays and
nearshore waters during the early summer. By fall, they disappear to the central depths of
the lake, where they spend the winter feeding on zooplankton before migrating shoreward
again in late spring.
After sea lampreys had eliminated most of Lake Michigan's large predator fish, the
population of alewives exploded throughout Lake
Michigan. During the early summer, these small fish spawn in harbors and nearshore
waters, disappearing by late fall to feed off the bottom in the central depths of the
lake. They migrate shoreward again in mid-March and April, completing the yearly cycle.
Alewives swim in dense schools and have been the major prey of the Lake Michigan's
trout and salmon. At the same time alewives have exerted overwhelming pressures on lake herring, whitefish, chubs, and perch -- species that compete with alewives for
the plankton and other small aquatic organisms that make up the diet of these fish.
The alewives found off of the Atlantic Coast are larger and meatier and have been used
for human consumption for years. Scientists are currently working on ways to make a smoked
or sardine-like food product from Great Lakes alewives. While Lake Superior's alewives
remain essentially a forage fish for trout and salmon, tons of the thin, bony fish are
already being harvested in Lake Michigan for animal food.