The Blueback Herring enters the Connecticut River to spawn at about the same time as American Shad. Peak blueback movement often occurs slightly after peak shad movement. Historically, river herring were a large and valuable fish commodity in the Connecticut River. Both states of Connecticut and Massachusetts have fishing moratorium (since 2002 and 2005, respectively) to allow the blueback to recover.
Herring tend to spawn on hard substrates in fast-moving tributaries of the lower Connecticut River at temperatures of 14° to 25° C. Presumably some of their spawning also occurs in the mainstem Connecticut River upstream and downstream of the Holyoke Dam, where swift-flowing habitats with hard substrate are available. Although, Blueback herring may also use more diverse habitats, often including flooded backwaters (such as the Oxbow).
The adults migrate back downstream immediately after spawning, and are capable of returning to spawn in subsequent years. The numbers of blueback herring along the entire East Coast has experienced a dramatic decline over the past decade. Numbers lifted at the Holyoke Dam peaked in 1985 when over 600,000 were lifted to a low of 21 fish lifted in 2006.
- Blueback herring are highly migratory at sea and swim in large schools, eating zooplankton such as copepods or small shrimp, as well as small fish.
- One way anglers tell the difference between blueback herring and their ‘sister’ river herring, alewives, is the dark color of the lining of their body cavities.