Alewife
Alosa pseudoharengus

The alewife is a member of the shad family and holds many traits that persist in this family. Oversized silver scales covers the whole body with a darker colouration along the back. Large eyes are situated very close to the mouth which helps it see the small zooplankton before feeding on them. It also has a deeply forked tail and a long anal fin. Total length is about 6" on average.

Usually this fish is of a robust physic that signifies a healthy and plentiful zooplankton abundance. With the recent decline in zooplankton due to the filtering work of zebra mussels and reduced pollution levels, today's alewife generally look much thinner then the drawing above. The head portion is the largest feature of the body for recent adult alwife.

History in the Great Lakes:

This fish entered Lake Ontario through the St Lawrance Seaway in the late 1800's (first reported in 1873). Until the mid 1900's, resident Lake Ontario atlantic salmon and lake trout managed to maintain numbers of alewife. With the fall of lake trout populations and atlantic salmon, the alewife was given the run of the lake. Also the upper Great Lakes were connected by shipping canals that helped spread the alwife throughout (Lake Erie in 1931, Lake Huron 1933, Lake Michigan 1949, and Lake Superior 1945). In the 70's the population of alewives exploded with the lack of natural predators. Beaches were littered with dead alwives during common spring water temperature fluctuations. To solve the stinky problem, soon coho and chinook salmon were planted throughout the Great Lakes to subdue alewife populations.

Today's Alewives:

In Lake Ontario alewife populations have seen ups and downs. In recent years a rebound of alewife populations have been linked to warmer winters (winter survival), decent stable water temperatures in the spring for successful hatches, and the advent of the spinny waterflea as a new source of food. It is said that alewives spend shorter time in the shallows to spawn in the spring due to ultra clear water. As well, zooplankton is harder to come by, which may account for the smaller, very mobile (here today, gone tomorrow nature) and  more spread out nature of today's alwife schools.

The original native alewife in the Atlantic are anadromous (live in saltwater and then migrate to freshwater to spawn). In Lake Ontario the alewife migrates from deeper water over basin areas to inshore spawning habitat in April. Spawning can occur as late as mid July, but is at it's peek during late June. Juvenile alwives also migrate inshore at this time.

Males reach maturity at age 2 and Females at the age of 3. Average Length of 6 inches at maturity.

Habitat for spawning is most often sandy beach areas or creeks and shallow back bays along the lake's shoreline. They will move in at night to spawn and move out during the day. Females usually appear at spawning grounds first, followed shortly by the males.

Eggs are dispersed over sand or gravel and are somewhat free to drift and are non-adhesive to the substrate. Eggs Hatch in 6 days in 60'F water temperatures. By fall they are 2"-3" long.

Information from "Freshwater Fishes of Canada" W.B.Scott and E.J Crossman, 1973