One hot sunny morning in late June, Amanda Higgs, a fisheries biologist with the state Department of Environment Conservation’s (DEC) Hudson River estuary program, was fishing for Atlantic sturgeon, the Hudson’s largest and most ancient fish. Once reaching a length of 14 feet and weighing as much as 800 pounds, the sturgeon evolved from an ancestor that dates back to the dinosaurs.
Sturgeons have been roaming the world’s oceans and rivers for 85 million years. For millennia, these oceanic fish have been swimming up the Hudson and other East Coast rivers in the spring to spawn, laying their eggs in the freshwater stretches above the salt line. But the past 150 years have done what millions of years prior could not — the sturgeon have been extirpated from many of their natal rivers and fished nearly to extinction.
Sturgeon bones discovered at archaeological sites along the Hudson indicate the fish was a significant food for native peoples 1,300 years ago. In the 19th century, sturgeon was harvested in huge numbers for its meat, caviar and oil. When the shad had been fished out, commercial fishermen switched to sturgeon as a cheap, plentiful food for the immigrant populations.
Overfishing for “Albany beef,” as this poor man’s victual came to be called, caused a population crash by the beginning of the 20th century. Similarly, the “caviar craze” of the 1890s decimated the Atlantic sturgeon in the Delaware River.
Fishing for sturgeon had resumed in modern times, and in the 1990s you could still order smoked sturgeon atNew York’s Oyster Bar. But fishermen were noticing that they were no longer catching juvenile sturgeon in their nets. In 1995 the Hudson River Foundation, a nonprofit organization, funded research by experts that showed the fish’s numbers were dwindling to the point where the sturgeon couldn’t sustain itself. According to the National Marine Fisheries Service at that time, the mean annual spawning stock was estimated at 870 — 600 males and 270 females.
The next year the state closed the Hudson River fishery. A coast-wide 40-year moratorium was instituted by the Atlantic Marine Fisheries Commission, a regional regulatory organization, in 1998. This past February, four of the five Atlantic sturgeon populations, including the Hudson’s, were declared an endangered species by the NMFS.
Tagging tales
Since 2006, the DEC has been tagging the Atlantic sturgeon during its June spawning run. On this particular morning, Higgs and her three assistants caught five male sturgeon in nets dropped from their boat off Norrie Point and Hyde Park. I was one of several reporters aboard Riverkeeper’s patrol boat, which pulled up alongside the DEC craft so we could get a close look at these fish.
Once caught, the fish, which averaged about six and a half feet in length, became surprisingly docile as they were slid into a narrow, water-filled pen onboard. A bottom-feeder that sucks up mollusks, crustaceans, worms, plants and small fish with a mouth that protrudes like a tube, the sturgeon seems crafted by a cartoonist. A pair of barbells drooped from flattened, shovel-shaped snouts. Small eyes swiveled to show their whites, and a squishy, gaping mouth sucked and gasped on the flat bottom of the head.
Yet the streamlined bodies, covered in beautifully patterned olive-brown scutes (a kind of tough cartilage), were surprisingly graceful, not at all like the skinny, prickly creature depicted in blue on the DEC’s omnipresent “Hudson River Estuary” signs. The heaviest fish — 68 inches long and 158 pounds — was missing a tail, possibly the result of a shark bite or propeller collision.
The next day the DEC’s sturgeon tagging program ended for the season. Higgs noted it was the best year yet, with a record 123 caught. All were males: females, far fewer in number, don’t move around as much and would require a different kind of net, Higgs said. At least a decade of sampling will be needed accurately to assess the fish’s population status. Nonetheless, since tagging began four years ago, the agency has noticed an encouraging increase in the numbers, she said.
From 2006 to 2008, the DEC attached sonic and satellite tags to some of the adult fish (presently, due to lack of funds, it is attaching metal tags donated by the U.S. Fish and Wildlife Service). The tags helped solve the mystery of where the fish go when they leave the river. The sturgeon tended to aggregate off southwestern Long Island, along theNew Jerseycoast, and offDelawareandChesapeakebays. Two tagged fish swam as far as Nova Scotia and off the coast of Georgia.
The DEC has also learned more about the sturgeon’s movements in theHudson. A previously unknown spawning ground offNewburghhas been identified. Some adult fish are returned to the river more frequently than expected. The DEC is also sampling juvenile sturgeon in the spring. Their seasonal movement has been tracked from West Point in the summer down to the estuarine waters of Haverstraw Bay and as far south as the Tappan Zee in the winter.
By correlating the locations of the sturgeon with a new, partially completed digital map showing the various habitats of the river bottom, the agency can target for protection those habitats preferred by the fish.
In their genes
Mitochondrial DNA analysis of the Atlantic sturgeon by Isaac Wirgin, an associate professor at New York University School of Medicine, has established that fish spawned from different rivers do have distinct genetic footprints, proving that sturgeon return to their natal river to spawn. In addition, Wirgin’s information reveals the extraordinary importance of the Hudson River variant of the fish. The Hudson accounts for one of the largest populations of Atlantic sturgeon, if not the largest, in North America. In tracing the origins of aggregates of ocean-caught fish back to nine rivers, Wirgin has found that 42 percent are from the Hudson. (The NMFS notes on its website that the only other relatively robust population that’s been measured is sturgeon in Georgia’s Altamaha River.)
Wirgin has also discovered aggregates of mostly Hudson River sturgeon near the mouth of the Connecticut River in Long Island Sound and off Fire Island Sound. Approximately 5,000 Atlantic sturgeon are caught in these nets each year, resulting in some fatalities. Such information is helpful in protecting the sturgeon from accidental catches in monkfish and other commercial fishery nets. Restrictions on fishing in these sturgeon areas could reduce the amount of bycatch, Wirgin said.
Boat collisions are also a problem, particularly in theDelaware River. Although the young fish are increasing in number, PCBs could be causing problems in some sections of the river, speculated Wirgin. By exposing fertilized sturgeon eggs to toxins at levels similar to what is found in the river sediment, he has researched the effects of PCB. The chemicals cause a variety of fatal deformities in the larvae, he noted.
Slideshow image of Atlantic sturgeon by U.S. Fish and Wildlife Service, Duane Raver.
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