Blueback herring are migratory fish, which occur along the Atlantic coast of North America from Nova Scotia, Canada to northern Florida. When rivers begin warming and reach about 57°F, adult blueback herring migrate or “run” up rivers to spawn in fast moving freshwater over hard substrates in large rivers as well as in small tributaries upstream from the tidal zone and even in brackish waters. Spawning runs up into Atlantic coastal rivers and estuaries, therefore, occurs in late winter (southern rivers) to late spring (northern rivers).  Depending on water temperature, the eggs hatch in 3 to 6 days. The young fish spend their first summer in freshwater until they are large enough, generally 3-4 inches, to start their journey back to the ocean. This juvenile freshwater period can range from 3 to 4 months, depending on where they were hatched and prevailing water temperatures. 

With the approach of cooler water temperatures in the fall (northern rivers) to early winter (southern rivers), most juvenile blueback herring begin their migration back out to the ocean. In some systems, juveniles will overwinter in the deep waters of estuaries or bays and their tributaries.?Once they are out at sea, they undertake seasonal migrations along the Atlantic Coast. The Gulf of Maine is a known summer feeding area for many east coast stocks. They stay in the ocean until they reach maturity at 3 to 5 years of age, and return to the river where they hatched to spawn a new generation of fish. Blueback herring have also evolved to survive the rigors of the spawning run in northern latitudes (north of South Carolina) and may return at a larger size to spawn in subsequent years. Repeat spawners are an important component of populations as larger females produce more eggs and help with population resilience under variable and changing environmental conditions.  

Blueback herring eggs hatch in 3 to 6 days. The young fish spend their first summer in freshwater until they are large enough, generally 3 to 4 inches, to start their journey back to the ocean. This juvenile freshwater period can range from 3 to 4 months, depending on where they were hatched and prevailing water temperatures.

With the approach of cooler water temperatures in the fall in northern rivers, to early winter in southern rivers, most juvenile blueback herring begin their migration back out to the ocean. In some systems, juveniles will overwinter in the deep waters of estuaries or bays and their tributaries.?Once they are out at sea, they undertake seasonal migrations along the Atlantic Coast. The Gulf of Maine is a known summer feeding area for many east coast stocks. They stay in the ocean until they reach maturity at 3 to 5 years of age, and return to the river where they hatched to spawn a new generation of fish.

The common length for blueback herring is 11 inches with the maximum reported length being 15.7 inches.

 The heaviest reported weight of a blueback herring is 0.44 pounds.

Blueback herring spawn in brackish water or freshwater rivers. They prefer swift stream flow and hard substrates for spawning sites.

Blueback herring feed on small ?shes, copepods and small shrimps.

Migration Behavior 

Blueback herring?is?a migratory species.?They?are?hatched?in freshwater,?then migrate to the ocean?where they grow and mature. They return to freshwater to?spawn.?