Acoustic Tags Prove Shortnose Sturgeon Returning to Penobscot

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Endangered shortnose sturgeon have rediscovered habitat in the Penobscot River that had been inaccessible to the species for more than 100 years prior to the removal of the Veazie Dam in 2013, according to researchers at the University of Maine. The U-Maine researchers confirmed evidence that 3 female shortnose sturgeon were detected in the area between Veazie (upriver of the dam remnants) and Orono (Basin Mills Rips), Maine in mid-October. Researchers had previously implanted these sturgeon with small sound-emitting devices (acoustic tags) to see if they would use the newly accessible parts of the river.

Among the most primitive fish to inhabit the Penobscot, sturgeon are often called “living fossils” because they remain very similar to their earliest fossil forms. Their long lives (more than 50 years) and bony-plated bodies also make them unique. Historically, shortnose sturgeon and Atlantic sturgeon (a related species also present in the watershed) had spawning populations in the Penobscot River as far upstream as the site of the current Milford dam, and provided an important food and trade source to native peoples and early European settlers. Overharvest and loss of suitable habitat due to dams and pollution led to declines in shortnose sturgeon populations and a listing as endangered under the U.S. Endangered Species Act (ESA) in 1967. In 2012, Gulf of Maine populations of Atlantic sturgeon were listed as threatened under the ESA.

Today, a network of sound receivers, which sit on the river bottom along the lower river from Penobscot Bay up to the Milford Dam, detect movement and location of tagged fish.