Blueback herring (Alosa aestivalis) are anadromous, migratory, schooling fishes believed to spend most of their life cycle at sea. Adults may return multiple times to their natal rivers to spawn. Blueback herring run at the same time as alewives, and together the two species of “river herring” provide a valuable fishery harvest for some tidewater communities.
Today, many communities in Maine and the Northeast are working to restore river herring to local waterways. While most of the focus is on alewives, which spawn in lakes, blueback herring also appear to benefit from increased access to river habitat. But very little is known about where juvenile blueback herring spend their time. Do they stay in the river or estuary for a period of time, or run right out to sea?
Wilson and graduate student Molly Payne Wynne studied returning adult blueback herring in seven Maine rivers, and analyzed their history of habitat use through otolith analysis. Otoliths are ear bones that provide a chemical “fingerprint” of the water through which a fish has traveled, recording time and place in layers like tree rings. Sea Grant funds supported laboratory analysis of 200 otolith samples.
Results, reported in the Canadian Journal of Fisheries and Aquatic Sciences, revealed variable individual migration histories. Some fish went to sea in their first year, but the majority stayed in freshwater or low-salinity habitat, suggesting that conservation efforts need to address a broad diversity of habitats.
Sea Grant funds: $7,500
*This project was leveraged for a larger Sea Grant research project on river herring.