Molly Murray

The News Journal

Researchers believe fewer than 100 adult Atlantic sturgeon now return to the Delaware Bay and River for spawning each year

The number of immature juveniles in local waters at 5%2C700 to fewer than 1%2C000

River landings of sturgeon%2C harvested for eggs for caviar%2C peaked in 1888 at 6 million pounds. By 1901%2C sturgeon landings in the Delaware were 6 percent of that.

No one at the Army Corps of Engineers can recall a brush with endangered Atlantic sturgeon during maintenance dredging of the Delaware River ship channel – a process that has been ongoing for decades.

But on Sunday, a five-foot long, mature adult was sucked up by the dredge after the fish passed through a filter screen. The fish died in the journey through the dredge apparatus.

That was rare enough. But then, it happened again on Monday.

This time, it was an 18-inch-long juvenile, said Richard Pearsall, a spokesman for the Army Corps' Philadelphia District.

Because the fish are so rare and are listed as an endangered species, federal fisheries officials were contacted, the fish were recovered and corps officials "moved to a different section of the river" out of concern that more sturgeon might be in the area, Pearsall said.

In addition, they replaced the mesh screen over the drag head – the part of the dredge that pulls sand and sediments from the bottom – from 9 1/2 to 10-inch openings down to a smaller mesh of 4 ½ to 5 inches, he said. The mesh screen is supposed to keep larger fish out of the dredge suction equipment and protect them from harm.

The sturgeon were sucked up at the Delair Range, a section of the ship channel near Pennsauken, N.J., Pearsall said. Sturgeon typically live and feed at the bottom of the river.

"Because of the concerns, we moved to the Tacony range," several miles to the north, he said.

Maggie Mooney-Seus, a spokeswoman for National Fisheries North East Region, confirmed that two sturgeon had died as river dredging continued.

Mooney-Seus said a federal fisheries observer is aboard the dredge monitoring all operations.

The sturgeon carcasses were picked up by state environmental officials, who took samples, and then they were taken to Delaware State University for long term storage, she said.

Scientist Dewayne Fox and a team of graduate students have been tagging Atlantic sturgeon with tracking devices each spring before the fish move into coastal estuaries to spawn. The tracking project is designed to show researchers where the fish are going and when they move to specific areas.

In addition, state fisheries biologist Matt Fisher has been monitoring juvenile sturgeon in the Delaware River to see how the population is doing.

In 2009, he discovered a tiny Atlantic Sturgeon – the first confirmed evidence in 50 years of Atlantic sturgeon spawning in the Delaware Estuary.

Sturgeon are an ancient species, and were listed as endangered in 2012. Adults, which take as long a two decades to reach sexual maturity, spend much of their time in the ocean, but move into fresh water to spawn in the spring.

No one is certain exactly where spawning takes place in the Delaware estuary or whether females spawn every year. Each fish, however, has a genetic signature that is unique to the estuary where it was spawned.

Historically, Atlantic sturgeon have been found in all the major river systems along the Atlantic, from Canada to Florida. The Delaware River had the largest population and in the late 1800s, the fish were targeted for both flesh and their eggs, which were salted and sold as caviar. At the time, the Delaware River was the largest producer of caviar in the country.

River landings peaked in 1888 at 6 million pounds. By 1901, sturgeon landings in the Delaware were 6 percent of that. Fishing for Atlantic sturgeon was banned in Delaware in 1999.

Industrial uses along the river have also taken a toll on Atlantic sturgeon.

A recent News Journal review of documents from the Salem-Hope Creek nuclear plant found that workers found 23 Atlantic sturgeon in Salem's intake structure since July 1, including 11 dead and six others with sometimes grievous injuries. The numbers exceeded federal estimates made in 2010.

Researchers believe fewer than 100 adult Atlantic sturgeon now return to the Delaware Bay and River for spawning each year, with past studies estimating the number of immature juveniles in local waters at 5,700 to fewer than 1,000.

Reporter Jeff Montgomery contributed to this story.

Reach Molly Murray at 463-3334 or mmurray@delawareonline.com.

Follow her on Twitter @MollyMurraytnj.