Alewife

The alewife is a small herring having a greenish to bluish back and silvery sides with faint dark stripes. Although this species is overshadowed by other herring species in the marine environment, alewife are a key player in many freshwater lakes within which they have been introduced -- particularly the Great Lakes. Freshwater alewives, sometimes called sawbellys, are important as prey for popular game fish such as salmon and trout. They are extremely abundant in the Great Lakes, and are often regarded as a nuisance when large masses of these fish wash up on shorelines following large spring die-offs. Currently, alewives are a key player in a mysterious thiamine deficiency syndrome that has caused widespread reproductive failure in key native salmonine fishes, such as lake trout and Atlantic salmon. Alewives often contain thiaminase, which is an enzyme that causes thiamine deficiency in predators that eat alewives, yet mysteriously, alewives do not suffer from this thiamine deficiency. Ongoing research studies are underway to determine factors responsible for development of the thiamine deficiency syndrome.

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife

Alewife