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Unraveling mysteries of shortnose sturgeon

Shortnose sturgeon, photo courtesy Robert Michelson, Photography by Michelson, Inc.

Shortnose sturgeon (Acipenser brevirostrum) are found in most major river systems along the East Coast, from the Saint John River in New Brunswick, Canada, to the St. Johns River in Florida. Recent data from the University of Maine, Maine Department of Marine Resources, and the U.S. Geological Survey’s Conte Lab in Massachusetts have provided an intriguing view of the migration patterns and habitat use of northern populations of shortnose sturgeon.

Defying expectations

Contrary to the prevailing perception that they were confined to large coastal rivers, the data show these northern populations of shortnose sturgeon migrate to and use small coastal rivers as well. Researchers have documented extensive coastal migrations between the Kennebec and Penobscot Rivers as well as other small coastal rivers in Maine (e.g., Darmariscotta, St. George, Medomak, and Passagasawakeag), and the Merrimack River, Massachusetts, and rivers in New Hampshire (Piscataqua) and Maine (Fernandes et al. 2010, Zydlewski et al. 2011). Telemetry data from 2008 to 2010 in the Gulf of Maine indicate that up to 70 percent of adult shortnose sturgeon frequently moved between the Kennebec and Penobscot Rivers and that over half of these coastal migrants used small coastal rivers in between the two larger rivers. Telemetry data also indicate that 80 percent of shortnose sturgeon using smaller coastal river systems during these migrations moved more than 6.2 miles upstream (Zydlewski 2011).

Revelations that aid recovery

Although the motivations for their migration patterns are not well understood, these coastal migration data have revealed new and critical information on shortnose sturgeon population dynamics, habitat use, and life history. Managers will be able to use this information to more accurately identify critical habitat and potential habitat restoration projects, benefiting sturgeon recovery and with the potential to restore populations to what might have been their historic range.

The use of new river systems as potential foraging areas and refugia, as well as the potential expansion of spawning populations into additional river systems, are extremely positive steps toward recovery of shortnose sturgeon in the Gulf of Maine and eventually throughout their range along the East Coast.

Updated: November 22, 2013