Let's hear it for the shortnose sturgeon: A primitive fish makes a comeback
In the depths of the Hudson River, a primitive creature is reclaiming its territory.
Unlike more modern fish, the shortnose sturgeon has no scales—only leather skin and rows of bony plates. It grows up to 4 feet long, and sucks up insects and crustaceans with a tube-like mouth. The sturgeon's strange appearance did not deter fisherman along the East Coast, who more than a century ago sought it aggressively for caviar and meat. Pollution and the construction of dams made matters worse, and the fish nearly vanished from many rivers.
But the future of this ancient lineage may be looking up somewhat, according to a study published earlier this year in the open-access journal PLoS ONE. The authors estimate that about 60,000 of these creatures, which were put on the federal endangered species list in 1967, now inhabit the Hudson River.
That’s even more remarkable because in general, fish protected by the Endangered Species Act have a lousy record. So far, five species have lost their protected status—four because they went extinct, and one because it was reclassified. No fish has ever left the list for the right reason.
Records for the past three decades suggest that the Hudson contains one of the largest shortnose sturgeon populations along the Atlantic coast. So the results of the study didn’t shock those familiar with the river.
“I just have had zero questions about whether the fish have become abundant and the population is healthy,” said Mark Bain, the study’s primary author and a biologist at Cornell University. “It’s been an easy sell that there’s a lot of fish.”
“The Hudson River is probably the example of the fastest recovery,” said John Waldman, a fish biologist at Queens College, who worked for one of the study’s funding organizations. In some rivers, the populations limp along below a hundred. The caviar craze of the late 19th century coincided roughly with a period of industrial growth along many northeastern rivers.
The fishing, the pollution and the dams wreaked havoc on many populations. By the 1950s, so few shortnose sturgeon remained on the East Coast that the government concluded they had been eliminated from all rivers, except for the Hudson. But numbers were hard to come by until more recently.
Between 1975 and 1980, biologist William Dovel counted shortnose sturgeon and found a population of about 13,000 spawning adults, still much smaller than Bain’s estimate.
Then in 1993 Bain set out to study a different kind of sturgeon that lives in the Hudson. Atlantic sturgeon can grow up to 5 feet longer than shortnose, and were the primary targets of commercial fishermen. But rather than find Atlantics, Bain turned up nets full of shortnose—a good sign for one fish, a bad one for the other. A few years later, fishing for Atlantic sturgeon was prohibited.
Surprised at how abundant the shortnose seemed to be, Bain and his colleagues started officially counting them in 1994. Their work continued into 1997 with financial support from the Hudson River Foundation and U.S. Army Corps of Engineers. The researchers used mesh nets to randomly collect the fish throughout the river from June to mid-September. They also collected fish at their winter gathering site and their spring spawning grounds near Albany, just below the Troy Dam.
Once caught, the fish were measured and tagged. Based upon the nearly 7,000 fish caught this way, the researchers estimated a population of close to 60,000.
Using data generated by Dovel and from electric utilities’ fish-monitoring program from 1985 to 1996, the authors argue that shortnose sturgeon population increased more than 400 percent between the late 1970s and the mid-1990s.
A lack of dams, which block the sturgeon’s seasonal migrations on the lower Hudson River may explain part of the shortnose sturgeon’s success here, according to Bain. He also credits the protection from fishing offered by the Endangered Species Act.
“I consider it a success story in the Hudson,” Bain said of the Act. “I think we’re going to end up seeing over the next couple decades that some other rivers end up with healthy shortnose sturgeon populations.” Waldman also cites improvements in water quality. He sees a national pattern of fish recovering as waterways near urban centers have cleared up since the Clean Water Act of 1972.
“I don’t look at this like it’s an accident,” he said.
Ultimately, the decision about whether the shortnose sturgeon in the Hudson River has recovered—whether it can afford to lose its endangered status—is up to the National Marine Fisheries Service. The agency is preparing to initiate a status review of the shortnose sturgeon, according to Angela Somma, chief of the Endangered Species Division.
Currently, all shortnose sturgeon populations are treated as a single species, but the review could allow them to be managed individually. This way the fisheries service could handle a stronger population, like the Hudson's, separately from others—maybe even take it off the list, although the service is hesitant to suggest this is a possibility.
The biologist who conducted the counts back in the 1970s, William Dovel, said that humans have much less effect on wildlife, such as the shortnose sturgeon, than we believe. “Nature is resilient, not fragile," he said. "Fragile is the worst word you can use.”