Of course, when you are working on the largest cooperative project in the history of marine biology, a 10-year, $600 million census of all the world’s marine life, you need to know something about the tax regime in 14th century Czarist Russia.

Let professor Jesse Ausubel, cofounder of the project, explain.

“The czars used to collect part of their income from Russian Orthodox monasteries in barrels of herring,” he said. “People didn’t lie to the czar, so the monasteries on the Baltic and Black Sea kept very accurate records of herring catches and herring runs, back to about 1300.”

Now do you get it? If you want to make meaningful assessments of the state of the marine environment, it helps to be able to make comparisons over time.

As if the task of cataloging what lives now in the ocean is not big enough, Dr. Ausubel and the many scientists and others, from 80 nations, who are working on the project don’t just want to know what is there now, but what was there decades or centuries ago.

The records of the czars give a clue. So do shell middens left by indigenous populations over millennia.

“From those middens, the bones and shells earlier people left behind, you can reconstruct the size and to some extent the abundance of species,” said Dr. Ausubel.

And animals themselves leave traces. Salmon, for example, leave scales behind in the lakes and pools where they spawn. So scientists can take core samples in British Columbia and use them to estimate what the salmon populations may have been hundreds of years ago.

The point here is about scope. This project is way, way more than fish tagging.

It has involved the tagging of tens of thousands of animals, but it also has involved all sorts of other things.

“We’re using every technique. Sonar, acoustics, cameras, the chemical traces some animals leave, DNA,” he said.

“We’ve had hundreds of expeditions to all parts of the world, from the Arctic to the Antarctic to coral reefs. Several thousand scientists are involved in all. There are about 2,000 I would call very deeply involved and thousands more here and there.”

The project goes beyond what might usually be thought of as science. An archive has been put together, for example, of photographs of recreational fishers.

“When people go sport fishing, people often have their photographs taken with their catch. So we had teams to collect those,” he said.

And those can be depressingly instructive.

“When you look at the pictures out of Key West, Florida, example, you can watch the size of the groupers decline as you look at the trophy photos over the decades,” Dr. Ausubel said.

The census was first conceived in Woods Hole back in 1997 by Dr. Ausubel and his colleague Fred Grassle, and it kicked off in 2000, with the goal of producing results by 2010. They now are in the final stages, collating tens of millions of records.

Along the way, the project has spawned a movie, which will have its national release through Disney on Earth Day next year, and has grown to become, as he says “the most comprehensive description ever of life in the ocean.”

And next Tuesday at the annual meeting of the Vineyard Conservation Society, Dr. Ausubel — a lifelong seasonal visitor to the Vineyard and VCS board member — will speak, present a preview of the film and report on what has been achieved.

“It gives the first A-to-Z list of all the known forms. It will be something like 230,000, maybe as many as 250,000.

“Since the census began we’ve discovered more than 5000 new species. Squid, fish and all kinds of things,” he said.

Impressive as that sounds, he emphasized there was still vastly more yet to be found.

“There are now about 16,000 named species of fish, and we estimate there might be another 4,000 species of marine fish still to be discovered,” he said.

And they are the obvious life forms. There are probably tens of thousands of undiscovered marine worms, and hundreds of thousands or millions of different bacteria, viruses, and such “very small stuff.”

“The age of discovery is not over,” he said. “The diversity of marine life is beyond words.”

But the census is about two other things besides diversity: distribution and abundance.

And on the latter score, the news is not good.

The major problem is not pollution or global climate change, with its attendant increases in water temperatures and acidification that will be long-term problems for the marine environment.

“The major problem is what I call the democratization of sushi,” he said.

“When only the emperor of Japan ate sushi, there wasn’t much of a threat to marine life. But when a couple of billion people have enough income to enjoy seafood, then you have a problem.

“The biggest challenge in 2009 is the human belly. With refrigeration and air transport, a lot of people can enjoy seafood.”

Out of the 230,000 forms of life, only a couple of thousand are important to commerce, like salmon or swordfish, but many of those species are under heavy pressure.

On the upside, though, Dr. Ausubel said, the oceans have remarkable recuperative powers.

“It’s very hard to make something go extinct in the oceans. They are very big and fishing becomes uneconomical if things are very scarce. So if you leave the oceans alone, life does grow back, if not always to the exact regime that existed beforehand.”

He cited the example of the Waddensee, near Denmark and Germany, which medieval prints showed to be rich in marine and bird life, but which had become a desolate mud flat by 1900.

“Now it is again rich with marine and bird life,” he said. “Nature abhors free energy. If there’s heat coming in, the phytoplankton will grow, and the zooplankton will eat them, and so on. Finally, you’ll end up with tuna and swordfish.

“If you leave it alone, it will bounce back, sometimes very quickly.

“Look at what happened in the north Atlantic fishery after World War II. There was very little fishing during the war, and in 1946 and 1947 they had huge catches.”

Of course, when you are working on the largest cooperative project in the history of marine biology, a census of all the world’s marine life, you need to know something about medieval prints of Danish mud flats, and the history of the Second World War.

The Vineyard Conservation Society annual meeting will be held at the Wakeman Center Tuesday beginning at 5:30 p.m. As well as Professor Ausubel’s talk, there will be a light dinner. For information call 508-693-9588.