The Secret Life of Lobsters (9 page)

I
f Bob Steneck were a lobster and wanted to cover his butt, what sort of shelter would he choose? Something that was easy to back into and defend from attackers. Bob sawed a PVC pipe into foot-long sections and tacked a rubber flap over one end of each piece. Donning his scuba gear, he descended underwater with his tubular homes and arranged them on a barren expanse of sediment in two rows, widely spaced. The rubber flaps were on the outside ends, so the entrances to the pipes faced inward, toward a kind of public square. It looked like a nice neighborhood.

Bob had no business building lobster neighborhoods. He'd been hired at the University of Maine as a marine ecologist in 1981 to study more arcane matters, like how long it took a sea urchin to eat a leaf of kelp. Bob had already made a name for himself piecing together an epic battle between coralline algae and vegetarian snails in the Caribbean, an evolutionary arms race that had transpired over millions of years. When Bob arrived in Maine he set out to examine the feeding patterns of herbivorous echinoderms and gastropod mollusks—the sort of blobs in shells that were known locally as urchins, snails, or limpets—but on his dives he was constantly distracted by lobsters. In the Caribbean Bob had sometimes glimpsed clawless spiny lobsters, but in Maine the lobsters were so plentiful and active that he had a hard time not playing with them. The animals seemed happy to oblige. When Bob checked his newly constructed neighborhood the
next day, a pair of claws and antennae were poking out the entrance of every pipe.

“Shit,” Bob said to himself, “why the hell am I studying limpets?”

Getting underwater had been an obsession for Bob ever since his boyhood summers at his grandparents' house on Lake Hopatcong in New Jersey. By the age of ten Bob had set a family record by swimming the four miles across the lake and back, but the surface of the water wasn't what interested him. He devised a makeshift scuba tank from a plastic-lined canvas sack. The buoyancy of the air-filled bag prevented him from reaching the bottom, so he tied window-sash weights made of lead around his waist to drag him down. His friend on shore was supposed to replenish the air in the bag through a garden hose attached to a bicycle pump. Bob had been on the bottom watching a crayfish for more than an hour when he got a headache. Surfacing, he found that his friend had abandoned the pump and gone fishing.

Now in Maine, Bob tried observing lobster behavior the same way he'd watched crayfish as a kid. Even with proper scuba gear, however, it was nearly impossible because lobsters could detect the minutest movements of water. If Bob tried to sneak up on a lobster that was foraging or searching for a shelter, the animal sensed the pressure waves emitted by the bubbles from Bob's scuba regulator, stopped what it was doing, and turned to face him, its claws raised.

Bob wasn't the first scientist to encounter this problem. Poring over books and journals in the library, Bob discovered that little was known about the behavior of the American lobster in the wild. But scientists had managed to learn some astonishing things about the way lobsters used habitat. In particular, lobsters boasted an impressive repertoire of excavating and remodeling skills. By spreading its mouthparts and front legs into the shape of a bulldozer blade, a lobster could shove sand or gravel from a burrow to enlarge it and erect barricades against intruders. Lobsters were also efficient stone movers. By carrying pebbles with their mouthparts or rolling larger
chunks of rock, they built perimeter fences and blocked off strategic openings in a burrow.

When faced with open terrain lacking natural crevices, a lobster was capable of creating its own burrow, though this was a time-consuming process. Like a dog digging for a bone, the lobster scratched the sand or mud out with its front legs and flung it back between its hind legs, where it piled up under its tail. Between bouts of digging, the lobster fanned its swimmerets to clear excess debris, a cloud of sand billowing out behind it. Lobsters were partial to a home with an escape hatch—an exit in the back that was small enough not to require constant defending, but that allowed the lobster to slip out in an emergency. If the crevice or hollow didn't come equipped with a back door, the lobster would often excavate one.

Bob chanced upon several papers written by Stanley Cobb, a marine biologist at the University of Rhode Island. Stan Cobb's research suggested that the American lobster's defensive strategy was governed partly by the desire to have its body touching things and partly by the desire to avoid light. The result was an affection for the coziest and gloomiest recesses of the seafloor, which provided defense not only against predators and other lobsters but also against the tidal currents that could rip through an underwater channel like blasts of air through a wind tunnel. Hiding under a flap of seaweed would suffice in a pinch, but a low-ceilinged rock hollow was best. Stan's experiments with clear and opaque domes demonstrated that darkness was more important to lobsters than snugness, but a lobster under bright lights would rather back itself into a glass jar than wander in the open.

Neglecting his urchins, snails, and limpets, Bob enlisted the help of several scuba divers and took a census of lobsters on the seafloor between Casco Bay and Penobscot Bay, near his office at the Darling Marine Center, the University of Maine's coastal lab for ocean science in Walpole, Maine. It didn't take long for Bob and his divers to realize that there were good neighborhoods for lobsters, where the population density was
high, and bad neighborhoods, where lobsters were scarce. Not surprisingly, the good neighborhoods tended to be boulder fields with lots of nooks and crannies. The bad neighborhoods tended to be featureless bedrock or flat sediment with nowhere for a lobster to hide.

Bob had earned his Ph.D. at Johns Hopkins University in ecology and evolution. He'd learned that an ecologist's first job was to notice a pattern in nature and then simply to observe it for a while. Such patterns usually had to do with the distribution and abundance of organisms—where, and how many? Once Bob had observed a pattern to his satisfaction, his next task was to come up with a hypothesis about the natural process that might have created that pattern. Finally, in testing his hypothesis, he would try to identify a concrete mechanism in nature that was responsible for the process. The hope was thereby to gain some insight into how organisms had evolved, especially in relation to each other.

It was a simple creed—patterns, processes, mechanisms—and examples were everywhere. When Bob, wearing shorts, strolled through a field and stumbled into a patch of thistle, his mind didn't stop at “Ouch.” The thorns drew his attention to the pattern of distribution and abundance of different plants in the field. That suggested a process—grazing by animals. The mechanism that drove the process was the mouth of the animal, the tongue and flattened teeth evolved perfectly for munching grass. In turn, the perfect defense against that mouth was to evolve thorns. Thistle could take over a field because it had become more resistant to grazing than other plants. It hadn't taken Bob long to realize that the only constant in his line of work was that populations of organisms were always in flux.

Now Bob had noticed a pattern in the distribution and abundance of lobsters. The seafloor had good lobster neighborhoods and bad ones. Bob wondered if the terrain of the seafloor itself might even control the number of lobsters that could live in a given area. Young lobsters might need swaths of small rocks for hiding, older lobsters bigger boulders.
Lacking either, they would jog off in search of more protective terrain.

Bob sawed up more PVC pipe and built additional lobster neighborhoods on the sediment. He had commandeered a leaky old houseboat from the Darling Marine Center, and now he anchored it above his arrays of pipes. Bob set up a generator on the boat and ran a video cable into the water. On the bottom it was attached to a miniature ROV—a remotely operated vehicle—with tiny propellers, low-intensity lights, and video cameras, none of which bothered the lobsters. Instead of distracting the animals with his scuba bubbles, Bob could sit aboard the houseboat all night long, hunched over the glow from a television set, and fly the ROV over the bottom to watch what the lobsters were doing in the neighborhoods he'd built for them.

 

The new house on Little Cranberry Island was white with blue trim, square and snug, set back from the road at an angle. Bruce Fernald put his arm around Barb as they gazed at it. They could hardly believe it was finished. They'd hired a couple of friends to build most of the house, one of them an island contractor and the other Bruce's former sternman with the predisposition for puking. The man was much happier on a roof than in a boat.

Bruce and Barb had assisted with the construction of the house by pounding nails and painting. Barb planned to plant a garden in front. Bruce had outfitted the back with a basement entryway for carrying his lobster traps, buoys, and coils of rope in and out. The living room was cozy, with a low ceiling for easy heating. In the kitchen, sunlight streamed onto the breakfast table by the window. Next to the sink was a VHF marine radio, and from the roof rose an antenna so Barb, now retired from lobstering, could call Bruce on the boat. The house was nestled in a stand of spruce that served as a buffer against winter winds. The blanket of trees stretched for half a mile down the road to the island's seaward beach, where a bar
ricade of gray cobblestones kept the ocean at bay. Two or three of the island's other young lobstermen had built houses nearby.

The wedding took place in July 1979, on what began as a foggy day. As people gathered on a lawn by the shore facing Mount Desert Island, the fog lifted, leaving a lacework of clouds hung like a bridal veil, curving with the contours of the Mount Desert hills. Bruce, solid and beaming, sailed across the grass in a trim three-piece suit of sky blue. Barb, elegant and giddy, was at his side in an off-white eyelet dress with a camisole top. She clutched a bouquet of island daisies and roses in one hand and Bruce's forearm in the other. Virtually the entire island community encircled them on the lawn. After the ceremony a metal skiff with an outboard motor pulled up to the rocky beach and took Bruce and Barb on a joyride around a neighboring island. July was the beginning of the trapping season, and for now a boat ride was all the honeymoon Bruce and Barb would get.

The wedding was a joyous celebration for the community, but back aboard their fishing boats the young lobstermen of Little Cranberry worried. They knew that seventy-five miles down the coast, scientists at Maine's Department of Marine Resources had been studying the lobster population. The Little Cranberry lobstermen were finding plenty of lobsters in their traps. Nonetheless, the scientists' prognosis for the future was not good.

 

To find out how the lobster population was faring, scientists at Maine's Department of Marine Resources had tagged and released lobsters and then put up “wanted” posters at the docks, asking fishermen to report those animals if they were caught—a clue to the rate at which lobsters ended up in traps. In addition, the scientists hauled some lobster traps of their own and analyzed the catch. They also traveled the coast, recording the size of the lobsters that fishermen sold at the wharf. Back in the lab, they dissected big and small lobsters to determine the size at which a lobster's reproductive organs
became functional. And they noted the size of the lobsters that extruded eggs while in captivity, to determine how large a female lobster had to grow before she was capable of bearing young.

The scientists made two crucial findings. First, if their statistics were correct, the lobster industry's annual harvest was composed overwhelmingly of lobsters that had just molted up to the minimum legal size. In Maine the smallest legal lobster was defined as an animal whose “carapace length” was at least three and three-sixteenths inches. In the 1800s lobsters had been measured from the tip of the bony spike between the animal's eyes to the end of its tail flippers, but this definition had proved too easy for fishermen to fudge. In 1907 the method was changed to the length of the carapace, which is the single large section of shell that encompasses the lobster's thorax—often referred to by restaurant-goers as the “body” of the animal, to distinguish it from the meat-filled “tail.” To measure the carapace, a lobsterman would line up one end of his “gauge”—the brass ruler he carried aboard his boat—at the lobster's eye socket and measure back to the edge of the carapace. When a lobster had molted to become large enough to pass this minimum-size mark, it weighed, on average, just under a pound—a meal of modest proportions.

The scientists discovered that ninety out of every hundred lobsters that fishermen brought to the dock each year were these modest-sized animals, only just big enough to meet the measure. The other ten lobsters would be just one or two molt increments larger. With lobstermen saturating the seafloor with traps as never before, the scientists believed that few lobsters made it through the gauntlet of fishing gear to grow much bigger than the minimum size.

The second finding had to do with how soon lobsters became sexually mature, and it lent an ominous cast to the first finding. The geographic range of the American lobster extends from North Carolina to northern Labrador, near Greenland. In southern latitudes where the ocean is warm, the reproductive organs of lobsters begin functioning at a
smaller body size than in northern latitudes. In Long Island Sound, for instance, at a carapace length of three and three-sixteenths inches nearly all female lobsters have reached puberty and are capable of mating and extruding eggs. In the colder waters of the Gulf of Maine, however, the scientists calculated that only 6 percent of females were sexually mature at Maine's minimum legal size.

Combined, the two findings pointed to a devastating conclusion. Hardly any female lobsters in Maine got the chance to reach puberty—let alone mate and make eggs—before they ended up on someone's dinner plate. With fishing on the increase and catches in decline, the situation seemed grim. In the Gulf of Maine, the American lobster could well be teetering on the verge of a disastrous collapse.