On an open sea deck, with the rolling waves of Georges Bank a mere eight feet away, Jon Brodziak cuts, and with tweezers takes a bone from each of the two inner ears of a haddock.

He places them in a small envelope for future study.

Then he does it again with another haddock. And again.

The bone is the otolith, which is used to tell the age of the fish; it is a far better measure than length.

Mr. Brodziak, along with several other scientists, is in the middle of a six-hour shift on the Albatross IV, in the pitch black night on the open ocean.

The fishing occurs day and night at specific spots to assure 24-hour coverage. The scientists work around the clock, too.

They carry out their task with demeanors that would befit an operating room, in an area containing three tables with cutting boards and scales to weigh the fish, in a sheltered place on the port deck. They wear oilskins, rubber gloves, rubber raincoats, rubber pants and boots. The air is raw. The work station is just out of the spray, out of the wash of a sometimes troubled sea.

The work is serious, although at times levity brings relief to late-night tension. At times the repartee among the scientists is a little reminiscent of the old television series MASH. Despite the harsh weather, morale is high.

Data gathered on the Albatross IV - otolith by otolith, fish stomach by fish stomach - will provide crucial information to hundreds of scientists ashore who are studying the state of fish in these waters.

One trip by the Albatross IV is considered a snapshot of how the stocks are doing. The information gathered tells scientists what the fish are eating and how well they are surviving. Over time, the accumulated data becomes a tool to gauge whether management restrictions are working.

"The work we do is of great importance in understanding the state of all stocks in the water," says Linda Despres, the senior scientist on the cruise. "The work we do is the basis for all the subsequent science and rules and regulations that are enacted."

She also says: "Taking this information and combining it with the information we get from port agents and the observer program fills in one of three puzzle pieces. And it is an independent piece of the puzzle, while the other two are tied more closely to the commercial fishery."

Mr. Brodziak expands on the thought. "Managing fisheries is always challenging because populations are hard to observe," he says.

Stocks can be observed in several ways.

"One source of observation is to look at what the commercial and recreational fishermen are catching," Mr. Brodziak says. "We can sample the catch and evaluate their size and age. But we need to augment that information because the fishery are only catching the harvestable size."

He adds: "Another measure is to send out observers. Under Amendment 13, we have observers on about five per cent of the boats."

On this day in early April 2005, the 42-year-old ship cruises Georges Bank, collecting data on the status of the fisheries. It is a twice-a-year pilgrimage in which scientists - who spend much of their time at a desk or in a laboratory studying catch reports and gathering scientific data - get out on the sea.

The Albatross IV is a floating science laboratory. In its 10-day spring trip, she cruises 1,530 nautical miles, zigzagging back and forth across the bank.

There are many ways to take the pulse of the fishery, to see how well fish such as cod, haddock, yellowtail flounder and bluefish are doing.

Every species has its story, its state of well-being, its season. For the wide variety of hakes and a multitude of other fish species, scientists say they have to be out on the ocean to get the best view, the best data.

Since 1963, the Albatross IV or a similar vessel has gone out and gathered trawl samples from the waters across the northeast continental shelf, from Cape Hatteras all the way up to the Gulf of Maine.

"The sampling method is consistent through time," Mr. Brodziak says. "It is through this method that we learned in the 1970s that foreign fishing fleets were decimating the fisheries on Georges Bank. It is one of the reasons why the Magnuson Act came into play."

Passed in 1976, the Magnuson-Stevens Fishery Conservation and Management Act mandates a national program for conserving and managing fisheries to allow for optimum yields on a continuing basis.

Through the trawl sampling, everything in the water is caught.

"We are basically sampling the ecosystem," Mr. Brodziak says. "We are setting trawls and doing plankton sampling. We are sampling all the species. We sample the noncommercial species like the long-horn sculpin and the sea ravens - the fish the fishermen don't want."

Twice a year, the ship cruises up the Atlantic seaboard, conducting four separate surveys on each cruise. The first survey began March 1 and included the waters off the Chesapeake Bay. The second leg included the waters off New York and New Jersey. This trip is the third leg, and includes the waters of Martha's Vineyard to all of Georges Bank. The fourth leg will be to the north, in the Gulf of Maine.

From Chesapeake Bay to the Gulf of Maine, crewmen lower a net into the ocean at 334 spots. Seventy-two of those spots, or stations, are on Georges Bank. Each tow is 30 minutes long. This practice of sampling the fish of the sea, which goes back 42 years, has generated impressive data, according to Ms. Despres.

Over time, different stocks can rise and fall. Some stocks are no longer a commercially viable resource, while others have done better. While catch reports on the dock show how many fish are landed, this trawl method is like taking the pulse of the patient, Ms. Despres says.

With its fine mesh lining inside, the trawl net catches everything, from the eldest haddock to those spawned in the past year.

Commercial fishermen are not permitted to use this method of fishing, for it is too effective in collecting what swims in the way of the net. Commercial fishing boats use large mesh nets, which allow all junior fish to escape.

At each station, the net is hauled aboard and the scientists evaluate the catch on a checker - a table with a walled counter. The fish are loaded into baskets and taken aside. Scientists then identify every species.

They inventory, count, measure and conduct examinations of each fish, from tiny shrimp the size of a dime to adult fish several feet in length.

With sharp knives, the scientists cut into stomachs and brains to evaluate and to collect samples. They open up the stomach of the fish to identify what it ate before being caught. They count partially digested fish and crustaceans.

With the haddock, Mr. Brodziak samples the eggs from all the pregnant females. The goal is to understand when females produce eggs with the best chance of survival - usually when they are older.

Mr. Brodziak, 42, is responsible for the assessment of haddock and has done it since 2001. He has worked in fisheries since 1990, and has spent much of his career studying haddock and Atlantic halibut.

Last year he was one of the first scientists to notice that haddock are showing signs of recovery.

Mr. Brodziak and his fellow scientists leave on Tuesday, March 29, from Woods Hole on this leg of the trip, a 10-day cruise to Georges Bank and back.

The vessel had been scheduled to leave the day before, but delayed its departure because of a severe rainstorm that descended on New England.

En route to Georges Bank, the ship speeds southwest down Vineyard Sound, with Naushon to the north and the Vineyard to the south.

In the afternoon, two miles north of Menemsha, the ship makes an experimental tow to be sure all the equipment aboard is working.

For half an hour the cables running to the net below shake back and forth. In the test tow the net comes up full of lances - a squirmy bait fish that is eaten by just about every fish in the ocean, from striped bass to bluefish to cod.

But this research trip will be marked more by what the ship does not find than by what it does find.

Four days later, on Friday, April 1, the ship is at Little Georges, 120 miles southeast of the Vineyard.

Tony Vieira, one of the professional fishermen on this trip who operates the research net, remembers huge landings of cod and flounder in the winter coming from Little Georges.

"Twenty years ago I remember you could get cod and a little bit of everything," he says.

On this trawl, the net comes up empty.

"This is crazy," scientist Kevin McIntosh says. "We are headed to the south by the canyons and all we've caught is one big haddock?"

On Saturday morning, April 2, the ship's net uncovers a pleasant surprise in Lydon Canyon, 180 miles southeast of the Vineyard. The net drops to a spot more than 300 meters deep. On its return, the net has a buckler dory. The large fish, bigger than a dinner plate, shines as if it were pressed with silver.

The ship then drags through Powell Canyon, bringing up redfish, lobsters and a huge boulder.

Mr. Brodziak explains that the redfish that he holds in his hands, measuring 18 inches in length, may be 50 years old.

More than 30 years ago, redfish were heavily targeted by foreign fishing vessels and almost disappeared. Their recovery has been slow because they grow slowly. "The stocks are only now coming back," Mr. Brodziak says.

"We have to find some fish," urges Charles (Charlie) Cartwright, a fisherman on board.

That night, the ship encounters the first sign of haddock. This is what the scientists have been waiting for.

But that day, and continuing into the following day, Sunday, April 3, a severe storm batters the vessel and scientists must suspend their around-the-clock work.

On Sunday evening the storm abates. Gannets return and follow the stern of the ship.

On Monday, April 4, the crew sees its first sunny day in a week offshore. The ship has traveled further east, to the eastern end of Georges Bank, and the net brings up plenty of haddock. Fishing boats work the area.

The net also brings up baskets of cod. Most of the fish are juveniles, only six inches in length. A harvestable cod must be 18 inches.

Mr. Brodziak takes note of the cod, but concentrates on his specialty: haddock.

Haddock is a cousin to the cod. While cod is known for being the fish that built a nation, haddock once were plentiful, too.

Mr. Brodziak looks for the numbers of haddock in every tow.

He is elated to find that these sea trawls have yielded two good year classes of haddock, with indications of a third good year class.

Each year a fish spawns is called a year class.

Mr. Brodziak holds out his rubber gloved hand and examines a tiny 2005 year class - a haddock that spawned earlier this year.

In all his years on the water, he says, he has never seen such a good sign of a new year class. He says it takes several good year classes to bring about the recovery of any fish. If haddock is to recover, there will need to be many good year classes.

The beleaguered cod, meanwhile, has not had a good year class in more than 15 years.

On Tuesday, April 5, the ship is in Canadian waters and the net comes up with plenty of haddock and a few cod.

On Wednesday, April 6, the crew in the pilot house spots a sperm whale. The spouting is a good field mark; only sperm whales shoot their spray forward. Minutes later, the whale dives, its tail sticking straight up into the air.

A 28-pound cod is landed, and the ship heads back into U.S. waters.

On the night of Thursday, April 7, the crew and scientists shift their attention to the trip home. The day was foggy with limited visibility, but tonight there is a spectacular sunset.

A party is held at the dinner hour for Capt. Jack McAdam. This is his last assignment as captain of the Albatross IV. Tomorrow when he steps onto the dock, his sea days will be over. Captain McAdam plans to take a desk job for the National Oceanic and Atmospheric Administration at the University of New Hampshire in Durham.

Scientists and crew members exchange telephone numbers and e-mail addresses. After dinner they talk about the Henry B. Bigelow, the new research vessel being built in Gulfport, Miss., to replace the Albatross IV. Scheduled to begin sea trials next year, she is a 208-foot white ship, larger than the 187-foot Albatross IV.

For three years, the two ships will work side by side, to assure that the continuity of science is carried correctly from the old ship to the new.

On this Thursday night, the scientists gather in their rubber boots and oilskins. They scrub down the work stations with bleach and wash them with fresh sea water. The next crew will conduct the final leg of the trip in the Gulf of Maine.

On Friday, April 8, the Albatross IV heads back to the dock in Woods Hole, passing the Steamship Authority ferry Martha's Vineyard on the way. At the dock, goodbyes are exchanged.

"When we all start off on a cruise, we are all strangers," says Ms. Despres. "At first we don't know our strengths and weaknesses. Three days into the cruise, magically we are a cohesive group and we know each other having worked side by side under the worst of conditions."

She concludes: "But the end of a cruise is sad. The team is going to dissolve and we will never have that intimacy again. We won't have that camaraderie again. Even though we may see each other on the shore, it will be different."