Blueback Herring (Alosa aestivalis) - Native

Adult blueback herring.

A 10-inch sea run blueback herring from the Connecticut River.

Identification. Very similar to alewife. Cheek patch wider than deep. Tongue is not visible in profile when mouth is held open. Eye width usually less than snout length. Lower jaw rises steeply within mouth. Usually a single dark spot on shoulder. Back usually looks bluish-gray on live fish, fading to silver on sides and white on belly. Peritoneum (lining of gut cavity) black.

Blueback herring.

A 5-inch juvenile Connecticut River blueback herring.

Size. Commonly 10 to 11 inches. State survey max. size 12.6 inches. Max. reported size 15.7 inches.

Distribution. Atlantic Coast from Nova Scotia to northern Florida. Some landlocked populations exist in other states. They make spawning runs up most large Connecticut coastal streams, where they are typically common to abundant. Landlocked populations were established for a short time during the 1950s in Crystal Lake (Ellington) and perhaps elsewhere, but no lake populations exist now.

Blueback herring distribution map.

All maps created in 2009. See CT DEEP Fish Community Data for updated distributions.

Habits. Adults spend most of their lives in salt water. They make spawning runs up their streams of origin typically during May and June in Connecticut. They typically spawn in faster currents and will penetrate farther upstream than alewives. Adults return to the sea after spawning. Juveniles feed in the rivers until fall, when they migrate to salt water. They can be caught by angling on a small jig or fly as well as by snagging or dip netting.

Comments. Blueback herring and alewives are often collectively referred to as “river herring” or by many anglers as “buckies.” Blueback herring and alewives are so similar that the color of the gut lining (peritoneum) is the only sure way to tell them apart. As with alewives, blueback herring numbers are currently low in Connecticut for reasons that are not fully understood. The best way to observe blueback herring spawning runs is to visit the base of dams on warm days in May during periods of low, clear water. Good locations are the Housatonic River at the Derby Dam, Sasco Brook in Westport/Fairfield at U.S. Route 1, the Salmon River at the Leesville Dam in East Haddam, and the Shetucket River at the Greenville Dam in Norwich.

Alewife and blueback herring peritoneums.

The color of the gut lining is the most certain way to tell an alewife (top, pinkish colored) from a blueback herring (bottom, dark colored).


Text and images adapted from Jacobs, R. P., O'Donnell, E. B., and Connecticut DEEP. (2009). A Pictorial Guide to Freshwater Fishes of Connecticut. Hartford, CT. Available for purchase at the DEEP Store.