Blueback Herring Life Histories
Blueback herring (Alosa aestivalis) is one of North America's anadromous herrings (see section on diadromy). These fish were among the most abundant "sea-run fish" in East Coast rivers and estuaries. John Waldman wrote about the loss of this vast diadromous abundance in his book, Running Silver.
Their range is from Florida to the Canadian Maritimes - quite impressive!
Together with a number of students, I've been studying bluebacks in the Hudson River watershed for some time now. This is the only of the anadromous clupeids that has managed to colonize the Mohawk River, the largest tributary to the Hudson. Occasionally it shows up west of the Mohawk, but shows no signs yet of land-locking.
Blueback herring display a great deal of phenotypic plasticity as regards their migratory movements, and we think also their spawning behaviors. Thought to be a spring-spawning species, the individual above was caught in the Mohawk River in early August, 2016. "Not supposed to be there!"
The YOY with the ruler were all collected in early September, 2009. Again, huge irregularity in spawning times is evident.
Blueback herring migration up into the Mohawk River may constitute one of the longest North American runs from the sea for this size of herring. Adults have been documented as far as 400 kilometers from the Atlantic, and the young-of-the-year have been seen even further up the Mohawk.
Amazingly, yearling individual bluebacks appear during the spring spawning run, along with the adults. You have to use the right kind of gear to catch them (electrofishing, or small-mesh nets). Otherwise, you wouldn't see this cryptic migration. Yet most of the young herring appear to return to the estuary or maybe even the Mohawk for a second visit to the nursery.
Currently, we are trying to document biogeochemical markers of habitat use in the Mohawk, the Hudson, and even the mighty Atlantic Ocean. We are grateful for financial support from the Mohawk River Basin Program of the NYSDEC and from the Hudson River Foundation.
Current project participants: Karin Limburg (PI), Cara Ewell Hodkin (PhD student, ESF), Evan Dlugos (ESF alumnus), and various volunteers
We conducted a feasibility study of using a "sonar camera" to count blueback herring migrating into the Mohawk via the lock and canal system in May 2017. The computer screen shows a clip of a sonar image of herring moving across the field of view.
