There’s good news for Mainers who love to catch, sell or eat lobsters. Both larvae and egg-bearing females are so numerous that lobsters might be regarded as a self-sustaining resource. Self-sustaining, that is, unless unexpected changes in ocean currents or temperatures or some disease epidemic upsets what looks like a bright future for the industry.

This according to a long, useful article in the current Atlantic Monthly by Trevor Corson, a writer and editor who draws on his two years of working on lobster boats off Mount Desert Island and extensive discussions with marine scientists. Mr. Corson takes a balanced view of the long-running dispute between many government specialists and most lobstermen (and lobsterwomen) over whether lobsters are being overfished and whether they are doomed to drastic depletion like haddock and cod in recent years. Record lobster catches, larger trap size, and the huge number of traps (now 2.8 million along the Maine coast), have stirred such worries. But Mr. Corson comes down strongly on the side of the harvesters.

Working with Bruce Fernald and Jack Merrill out of Islesford, he has watched the way they carefully notch the tail of any egg-bearing female and throw it back into the ocean. They also toss back any female whose tail is already notched, indicating that it is a proven breeder. A female that has just reached maturity can produce 10,000 eggs. An older, bigger female can produce 100,000. Size limits require them to throw back oversize males and females, to form a lasting stock of reproductive lobsters.

Scientists from the University of Maine and the University of Connecticut have been monitoring the number of mature breeders and lobster larvae and the in-between small organisms nicknamed super lobsters. Robert Steneck, a professor of marine sciences at the University of Maine, got interested in lobsters as a scuba diver along the coast of Maine. He and two ecologists, Lewis Incze and Richard Wahle, of the Bigelow Laboratory for Ocean Sciences at Boothbay Harbor, use student divers from UMaine to measure the lobster population by studying the abundance of larvae, baby lobsters and brooder stock. Professor Steneck also uses an unmanned robot submarine to make videos of how lobsters behave on the ocean bottom.

Another study quoted by Mr. Corson involved a “lobster-trap video” devised by Winsor H. Watson III, a zoologist at the University of New Hampshire, and his graduate students. They pictured what goes on in the trap in the long periods when it is not being set or hauled. To their surprise, they found that, far from getting caught in the trap, the lobsters freely come and go: Of the 3,058 lobster approaches to the trap, 45 actually entered. All but five escaped, and three of those were under the legal size, leaving two salable lobsters. Islesford lobstermen say they have known all along that the traps are inefficient and that there is a lot of coming and going.

You might ask why don’t the lobstermen devise a more efficient trap and catch all those lobsters rather than letting them go. The answer is that the catch is pretty good with the present traps. They are working all right the way they are, and their inefficiency amounts to one more effective conservation measure.