Fishermen harvesting science with sturgeon fishing
Bay's native population down to 500; recovery takes decades to occur
April 23, 2012
APP.com Kirk Moore
Bent over the transom of their boat, the crew of the Dana Christine strained to raise the net, and captain Kevin Wark knew he had what they wanted: a big female Atlantic sturgeon, heavy with eggs, perhaps heading to spawning grounds up the Delaware River.
Weighing in at more than 200 pounds, the fish strained the crew’s arms as they lifted it to a holding tank. “That’s a caviar fish,” Wark said, already thinking of what he could tell his boss, Delaware State University professor Dewayne Fox. “From the start Dewayne has wanted to find a spawning Delaware female. You could say it’s the sacred cow of this project.”
More than a century ago, Delaware Bay was one of the world’s biggest centers for caviar production. Back then, “this would have been a small one. The average female in the 1800s was 350 pounds,” said Matt Breece, a DSU graduate student, as he prepared to anesthetize the fish before extracting a tissue sample and implanting a tracking device.
At the height of the spring migration, New Jersey fishermen are catching, tagging and releasing up to two dozen Atlantic sturgeon every day off the Delaware beaches, helping to track the endangered species and build a body of scientific data so five East Coast breeding populations can be better protected.
The Delaware may have had a native population of 700,000 sturgeon in the 1800s, compared with today’s estimate of 500 animals, Fox said.
“It was the largest sturgeon producer in the world,” Fox said. “When the fishing was at its peak (in the 1890s) they were shipping caviar and sturgeon all over the world.” At a processing center dubbed Caviar — today’s Bayside in Salem County —“they built a railroad spur and shipped 12 to 15 cars to the markets in a day, and four to five cars of caviar.”
After taking that huge hit, sturgeon suffered from pollution as industry grew along the Delaware. The sturgeon’s own life cycle means any recovery is a slow process, said Ellen Pikitch, a professor and executive director of the Institute for Ocean Conservation Science at Stony Brook University on Long Island.
“They take a long time to reach maturity. One generation is like 20 years. With a species like this, it can take a long time to recover from overfishing,” Pikitch said.
Both the Delaware and Hudson rivers have cleaned up greatly thanks to the federal Clean Water Act, Fox and Pikitch said.
“You would have expected to see more of a recovery, so other factors must be at work,” Pikitch said. Today’s dangers include bycatch in fishing gear and strikes by boats and ships. Each year in the Delaware, 12 to 20 dead sturgeons turn up with apparent propeller wounds, Fox said.
But the sturgeon range so widely along the coast that protective measures need to cover a huge area as well, said Pikitch. Her work at tracking sturgeon with satellite tags has followed Hudson fish as far as Nova Scotia and Georgia.
“So if you want to recover these populations, you’re going to have to set your sights over a wider area than the rivers,” she said.
One of the oldest fish families on Earth, sturgeon were around with the dinosaurs and survived multiple extinction events. But the Atlantic sturgeon was brought low by industrial pollution in its river breeding spots, overfishing and loss of habitat. On April 6 Atlantic sturgeon were added to the federal list of endangered species, and now state and federal agencies are scrambling for ways to prevent accidental capture or killing of the fish — without forcing a shutdown of some 42 fisheries that may interact with sturgeon.
It’s a task for the long haul. Sturgeon take a long time to reach reproductive age — as long as 20 years — and females only spawn at four-year intervals. It’s been suggested recovering the Hudson, Delaware and other populations could take as long as 40 years.
And it won’t affect just fishermen. Opponents of plans to dredge the Delaware River are already capitalizing on the endangered species listing.
In the early 1990s, Wark was among Barnegat Light gillnet captains who caught sturgeon commercially for the fresh- and smoked-fish markets — and in so doing, discovered how to catch monkfish. Monkfish grew to become a major East Coast fishery, with a vibrant domestic market for “the poor man’s lobster” and strong export demand from Asian buyers.
Now the Endangered Species Act could curb gillnetting for monkfish — unless the National Marine Fisheries Service and fishermen can come up with a way to reduce the bycatch of sturgeon. Wark said gear modifications he’s tested show it should be possible to tweak gillnet use so fishermen can avoid getting sturgeon in their nets.
For the survey work, Wark and mate Mike Lohr of West Creek deploy nets with mesh of 9 inches, 12 inches, and 13 inches. While watching for sturgeon to appear ghostlike astern, the men pick out and throw back skates, horseshoe crabs and the occasional black drum.
“We got one!” Wark called out, his fisherman’s glee undiminished by 31 years on the water. As the net reel cranked the sturgeon closer, Lohr grabbed a rope snare to slip over the fish before it could slip out of the net.
With the rope loops, the crew drew the sturgeon up on the metal rollers that guide the net and slid it into the boat. Once they got the fish into the tank, Breece sprayed salt water from a big engine-driven pump into the tank, covering the fish and aerating the water.
After dissolving anesthetic in the water, it took a few minutes for the fish to settle down. Breece sanitized his miniature surgical set and made an incision.
Tissue samples from the fish go to DNA analysis that determines from which river population they came. Before closing the incision, Breece inserts a tracking transmitter. They come in two sizes, with battery lives of 6½ years or 2½ years.
Onshore receiving stations pick up signals as those implanted fish move along the coast, like motorists cruising through the E-ZPass tolls on a highway. Telemetry and physical tags on the fish tell scientists and fishermen where the sturgeon have been. The Delaware nets have intercepted fish from as far away as Georgia, and sturgeon caught and released off Delaware have been heard from as far north as Cabot Strait, the passage between Nova Scotia and Newfoundland.
During his years in the commercial fishery, Wark saw his biggest sturgeon come in at 492 pounds. He’s been at the research work with Fox for four years now, with nearly 500 sturgeon caught and released so far. Wark said he’s certain some bigger fish are still out there and could be located with the right gear.