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Sturgeon -- even dead ones -- a good sign
Overfishing, pollution drove fish from Del. 80 years ago


By MOLLY MURRAY / The News Journal
06/29/2005


Most people would not consider six dead fish washed up on the beach to be a good thing.

But J. Jed Brown sees it as a positive, if grisly, sign of hope for his search for mature Atlantic sturgeon in the Delaware River.

As many as a half-dozen large Atlantic sturgeon have been found in recent weeks along the river and bay, although all of the fish were dead. There were signs of trauma suggesting they had been struck by boat propellers, said Brown, the Delaware River fisheries coordinator for the U.S. Fish & Wildlife Service.

Still, "it's nice to know they're still out there," said Craig Shirey, Delaware's finfish administrator.

Brown, Shirey and other fisheries experts are trying to learn whether the sturgeon still are spawning in the river, or whether overfishing more than 80 years ago -- and decades of pollution since -- have driven the fish out of the Delaware. Their return would be a good sign of recovery for the river.

A year ago, Brown spent weeks on the river setting wide mesh nets near Pea Patch Island, hoping to catch a big, adult sturgeon headed to what scientists thought might be a nearby spawning area.

His nets snared only trash and tree limbs. Recent news about a sturgeon strain that once thrived in the river and bay is better, in a manner of speaking.

"If there are 100 fish and you're killing 10 of them, that's bad," Brown said.

Information lacking

No one is sure whether the fish are still breeding in the river because they often escape detection in traditional fish population surveys. The fish are not listed as a federally threatened or endangered species, and neither commercial nor recreational fishing groups are pushing for research money.

That means research on the species has been limited, making it hard for people like Brown or Dewayne Fox to even know where to look.

Fox, an assistant professor of fisheries at Delaware State University, pointed to research on Atlantic sturgeon done in 1925, when a scientist identified three key spawning areas in the Delaware: off Pea Patch Island, Penn's Grove, N.J., and Pedricktown, N.J.

"It's amazing when you look at this," Fox said. "This is the most recent state of the knowledge."

The sturgeon are an ancient species that Fox calls "dinosaurs with fins" because they were around when those extinct reptiles ruled the roost.

Atlantic sturgeon don't have scales like rockfish or weakfish. Instead, they have five rows of bony plates called scutes. The fish have a hard snout and four whisker-like protrusions they use as sensors. Sturgeon tend to scoot along in the darkness of the bottom, feeding from the bounty in the mud and sediment.

The Delaware River and Bay once were an ideal habitat for the fish, which fueled an enormous caviar and smoked sturgeon industry. Some estimates say that Delaware River fishing communities once filled as many as five railroad cars a day with sturgeon caviar. More cars were filled with smoked meat.

Overfishing killed industry

The fishery peaked in about 1890 and collapsed from overfishing in 1901, when sturgeon landings were just 6 percent of the 6 million pounds recorded in 1888. The population never recovered, mainly because it takes so long for females to reach spawning age. Scientists estimate it takes 14 years for a Delaware River sturgeon to reach spawning age, and female sturgeon don't spawn every year.

Once the breeding fish were depleted, other factors such as river pollution may have kept the population low.

The spawning area between Philadelphia and the Chesapeake & Delaware Canal became a dead zone. Pollution from sewage treatment plants and industry caused oxygen levels to drop to levels fatal for many fish. Sturgeon are particularly susceptible to low oxygen levels.

Scientists say a return by adult sturgeon would provide further evidence of the recovery of the river. Sturgeon live most of their lives in the ocean, but return to their birthplace to spawn.

Scientists believe Atlantic sturgeon are making a comeback in the Hudson River in New York. But those fish are a separate genetic strain. How the variety native to Chesapeake and Delaware waters is doing remains a mystery.

These days, even a dead sturgeon can be a welcome sign of possible recovery.

"It's promising that there are still some ghosts out there," said David H. Secor, an associate professor at the University of Maryland's Center for Environmental Science who has been studying sturgeon in Chesapeake Bay.

Secor said it's hard to know whether the big fish found in Delaware Bay are actually Delaware fish or migrants who may have wandered down from the Hudson.

Meanwhile, the hunt for live sturgeon in the Delaware goes on.

Delaware State University graduate student Phil Simpson's life has revolved around tide tables for the Delaware estuary for the last few weeks. He's been setting nets, searching for breeding-size Atlantic sturgeon to try to pinpoint where they might be spawning -- if they are.

A plan for study

His goal is to implant a specialized tracking device to follow a sturgeon and discover its spawning area. The tracking device -- about the size of two AA batteries end to end -- will track a fish for two years.

Simpson's adviser -- Fox -- said he is beginning to wonder if researchers aren't looking in the wrong place for spawners.

The river, he figures, is a different place from what it was when scientists in 1925 identified Pea Patch Island as a spawning ground.

The river is deeper now than it was in 1925, thanks to channel deepening. And the salt line is likely farther north than it used to be, Fox said.

Mature spawners seek out fresh water for egg-laying, because baby fish can't survive in salt or even brackish water.

Sturgeon eggs are sticky and females look for spots with a hard bottom to avoid a thick coating of sediment that could block the oxygen supply.

In the Delaware today, a hard rocky bottom would be found from the Cherry Island Flats off the Wilmington shore and north toward Philadelphia.

It is a very big river, and that makes it hard to find mature fish unless you know where to look.

"It only takes one or two fish," to begin solving the puzzle, Fox said. "There's hope."

Contact Molly Murray at 856-7372 or [email protected].

[ 06-29-2005, 01:07 PM: Message edited by: NIGHTSTRIKES ]
 

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Some estimates say that Delaware River fishing communities once filled as many as five railroad cars a day with sturgeon caviar. More cars were filled with smoked meat.
That's amazing! Too bad people couldn't see into the future to heed such senseless slaughter...

Interesting article, Steve. Thanks for sharing.

[ 06-29-2005, 02:26 PM: Message edited by: dante413 ]
 
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