National Geographic: One day last June, two researchers were towing a special sonar system up and down the Hudson River near Hyde Park, New York, the site of President Franklin Delano Roosevelt’s home, when they saw something pleasantly shocking.

They were helping state biologists assess whether the spawning or foraging of a fabled and endangered bottom-feeding denizen, the Atlantic sturgeon(Acipenser oxyrinchus oxyrinchus), was being disrupted when commercial vessels dropped anchor in a spot designated as a waiting area to manage ship traffic.

The anchorage, established in 1999, happened to be located in a stretch of the Hudson that is one of the most important spawning grounds in its range along the coast from Florida through Canada’s maritime provinces. More anchorages were planned elsewhere in the Hudson….

The sonar revealed a sturgeon roughly twice as long as anything seen that day—confidently estimated at just over 14 feet from nose to tail tip. That’s a size that, even decades ago, even a century ago, was considered a rarity. But now, it was unimaginable given what this species had endured….

The debate over adding anchorages along the Hudson is on hold for now after fierce opposition from environmental groups and scientists, including a cautionary 2016 letter to the Coast Guard from Madsen and Fox, who’ve been doing surveys around Hyde Park for several years.

But any harm from dragging anchors would be just one of a host of far broader assaults on this species, and sturgeon worldwide, over the last century. Read more.

(Photo, Courtesy of National Oceanic and Atmospheric Administration)