Blueback Herring Identification Guide
Tell blueback herring apart from alewife and shad using its dark blue-black back and smaller eye relative to snout.
Read the full Blueback Herring encyclopedia entry →
Key identification features
- Slender, laterally compressed body with a deep steel-blue to blue-black back, darker than most other river herrings
- Bright silver sides fading to white on the belly, with a single faint dusky spot just behind the gill cover
- Eye diameter roughly equal to or smaller than the length of the snout, a subtler eye than alewife shows
- Deeply forked tail and a row of scutes forming a keel along the belly
- Adults typically 20-30 cm, similar in size to alewife but slightly more slender
Common look-alikes
- Alewife — greener, paler back color and a noticeably larger eye relative to the snout
- American shad — larger overall, deeper-bodied, and usually shows a trailing row of small spots behind the main shoulder spot
- Atlantic menhaden — much deeper-bodied with a larger head and more strongly serrated belly keel
Where you'll see one
Blueback herring are anadromous along the Atlantic coast of North America from Nova Scotia to Florida, spending most of the year at sea and returning each spring to spawn in coastal rivers and streams, often alongside alewife.
Frequently asked questions
What's the most reliable way to separate blueback herring from alewife?
Compare back color and eye size together — blueback herring shows a darker blue-black back and a smaller eye relative to the snout, while alewife has a greener back and a larger eye.
Can body size alone tell them apart?
Not reliably — the two overlap heavily in size, so back color and eye proportion are much better field marks than size alone.