NANTUCKET, Mass. — Thankfully, alarm about the sensibilities of lobsters does not appear to have reached Nantucket. Despite a weakening economy, wholesalers and retailers are reporting that sales of the hard-shelled critters are up, as are prices. Since lobster is the most important commercial fishery in the Northeast, with total dockside sales in excess of $350 million and overall industry revenues in the billions, this is good news.

While there are numerous other issues facing lobster fishermen, the brouhaha raised by Whole Foods and others over humane treatment seems far down on the list. Charles Sayles III, the biggest lobster vendor on Nantucket, practically snorts with amusement when asked if lobsters mind being plunged into boiling water. He says, “I never heard one scream,” and points out that lobsters’ brains are rudimentary, lacking the mechanism that records pain in humans.

Though its sensory organs may be simple, everything else about the life of a lobster seems immensely complex. For a creature that looks like a survivor from the Ice Age, lobsters are more delicate than one might guess. Consider: A large (old) female lobster may produce as many as 100,000 eggs at a time, but as few as four may make it to “legal”size, or about one pound. It takes five to seven years for a lobster to reach adult status, and during that time they are vulnerable to various predators, toxic substances, and changes in water temperature.

For those who work to protect the species, and the thousands of jobs that depend on it, the data on just how these factors impact lobster stocks is maddeningly contradictory. While New England waters are universally warming, the change in some areas appears remarkably beneficial, while in others it has been a disaster. It turns out to be a matter of degree.

Marine biologist Diane Cowan heads up the Lobster Conservancy, and has studied juvenile lobsters in Maine for fourteen years. (She’s especially keen on donning a dry suit in the middle of February, nipping into the frosty waters of her home state, and counting the little guys hiding under rocks. She says the water is clearer at that time of year.) Over about the same period, the Maine lobster catch has grown to 67.3 million pounds in 2005 (valued at $311.6 million) from 28.1 million pounds in 1990 ($61.6 million).

The rapid rise has caused concerns about stock depletion. Astonishingly, in that period Ms. Cowan has witnessed a four-fold increase in the juvenile lobster population in her area. That sounds pretty good, but, according to Ms. Cowan, the increase may only be temporary.

A warming trend of 10 degrees Fahrenheit in the waters off Maine just in the past seven years has created perfect conditions for the maturation of young lobsters, causing the growth in population. “If the temperature rise in Maine continues” warns Ms. Cowan,”we’ll have a problem. If the water gets too warm, lobsters won’t mate.”

Support for that concern stems from the severe downturn in lobster catches in the waters south of Cape Cod and into Long Island Sound. According to Bill Adler, head of the Massachusetts Lobstermen’s Association, warmer waters, increased predators and the use of pesticides to try combat the West Nile virus clobbered the lobster population in the region during the 1990s, resulting in the loss of about half of the fishing fleet.

Today, measures taken by the industry have seemingly reversed the decline in the region. Fishermen have taken extra steps to protect the population, including notching the shells of egg-laying females before returning them to the ocean, alerting others to their capacity to reproduce, and not harvesting especially large specimens.

In an industry that prides itself on having adopted sensible conservation measures as early as the late 1800s, groups like Mr. Adler’s concern themselves with fending off legislation perceived to be unnecessary and interfering. Even Ms. Cowan applauds the fishermen’s culture of conservation, which she attributes to the tight-knit community of family-owned firms.

Meanwhile, Mr. Adler is also fighting potentially threatening offshore developments. For example, his group opposes three LNG terminals proposed for Massachusetts Bay, in the middle of a prime lobster fishing area. Because of security concerns, such installations would be forever off-limits to fishermen.

These are not the only challenges faced by lobstermen.Trapping lobsters is a tricky business. For one thing, lobsters aren’t really trapped at all. Underwater videos have demonstrated that most lobsters can enter and exit the traps at will, and often go in to enjoy a hearty meal, only to leave before the trap is pulled.

This is especially annoying these days, when the cost of herring and other bait fish has gone through the roof. The prices of marine fuel, dockage, boats, and traps have also soared in the past few years. Despite strong volumes and prices, lobstermen are struggling to maintain margins.

The fishermen have no ability to influence pricing, and are at the mercy of the marketplace. Dave Madden, who runs the wholesale business of the Lobster Trap, Cape Cod’s biggest wholesale company, says prices are driven by demand. He is currently paying co-ops about $4.75 a pound; they in turn are buying from the boat at about $4 a pound. Retail prices vary all over the lot, but Mr. Madden says that supermarkets are charging $5.99 to $8.99 a pound. High-end shops like Sayles Seafood in Nantucket charge $12 a pound, but also cook the lobsters free of charge.

Though the industry is relatively healthy today, the future is clouded by warming water temperatures and other environmental hazards. Near term, an economic slump may weaken demand. As Mr. Madden points out, no one needs to eat a lobster. The good news for fishermen is that a great many people choose to.