Results of Blueback Herring Transmitter Implanta

Though blueback herring (Alosa aestivalis) were not recently listed under the Endangered Species Act, concern remains over historically low abundances.  A significant blueback population reproduces within Virginia’s James River, an act that necessitates passage through the Norfolk Naval Base and its related pile driving activities.  In 2013, 46 herring were implanted with Vemco™ V7 acoustic telemetry transmitters to attained temporal and spatial data. Nine were orally implanted and 39 were surgically implanted using three varied techniques. Herring staged in the oligohaline zone prior to upriver and downriver migrations during late April and May and displayed equal residence periods independent of immigration time. Four of the 9 orally implanted fish were last detected in the Chickahominy River where tagged, 4 in the James River and one in the Chesapeake Bay. Nineteen of the 39 surgically implanted fish were last detected in the Chickahominy, 10 in the James, two in the bay and two in the Atlantic Ocean.  Three herring, all of which underwent similar surgical procedures, were detected in life history appropriate locations off of New England in late summer and winter. Numerous predators, illegal netting and a dam passible on high tides likely explain some of the poor tracking results.