About Alosa pseudoharengus (Wilson, 1811)
Size
Alewife (Alosa pseudoharengus) reach a maximum standard length of roughly 40 centimetres (16 inches), with a typical standard length of around 30 centimetres (12 inches). The front portion of their body is deep, and larger than the front bodies of other fish that live in the same waters.
External Coloration
Alewife have bronze-colored heads, and a dorsal coloring ranging from grey-blue to greyish green. A dark shoulder spot (humeral spot) is often present on their body.
Tongue Structure
Their tongue has no teeth.
Peritoneum Characteristics
Their peritoneum (a membrane that lines the abdominal cavity) ranges from light-colored with spots to a dusky appearance; this internal feature distinguishes alewife from the closely related blueback herring (Alosa aestivalis), which have a dark peritoneum.
Otolith Shape
The alewife's otolith (ear stone) is shaped like the letter L, which differs from the hooked otolith shape seen in A. aestivalis.
Eye Size
Alewife also have larger eyes than A. aestivalis; in Alosa pseudoharengus, the width of the eye often exceeds the length of the snout.
