The Secret Life of Lobsters

by Trevor Corson

  Water flow inside the bowl is dominated by a huge, gulfwide gyre that constantly circles counterclockwise along the rim. Water from the North Atlantic enters the gulf across the Scotian Shelf and along the northern wall of the Northeast Channel and flows up the coast of Nova Scotia, past the mouth of the Bay of Fundy, and southwest along the Maine coast. The northwest leg of this gyre is a rapidly moving plume of cold water that oceanographers call the Eastern Maine Coastal Current.

  About two-thirds of the way down the Maine coast, much of the water in the Eastern Maine Coastal Current is deflected away from shore into the interior of the gulf. The rest continues down the coast in a warmer, slower plume called the Western Maine Coastal Current. Off Cape Cod, a small amount of this water exits the bowl through the Great South Channel, but most of it turns east and then north, flowing back up the inside edge of Georges Bank. Some of the water that was deflected from the Eastern Maine Coastal Current rejoins the gyre here.

  The gyre flows northward and returns to the Northeast Channel, where much of the water exits the gulf and flows back into the North Atlantic. Some of it remains inside the gulf to cycle through the gyre again. The currents inside the gulf are chaotic, and a myriad of eddies and vortices complicate their movements. Oceanographers have calculated that an average parcel of water spends about one year traveling inside the gulf before it leaves.

  When the lobster hatching season begins, usually between mid-June and early July, large numbers of females carrying fully developed eggs undergo abrupt contractions of their tail muscles during the night. Over the course of a week or so, these nocturnal contractions shake each lobster’s thousands of embryos free. The embryos are soft and round when they break through the outer seal of the egg, but within a few minutes they assume the shape of larvae, pointy-tailed and shrimplike.

  A first-stage lobster larva can detect the gravitational pull of the earth and swims upward and away from the bottom, beating its paddlelike appendages furiously. It can also detect light, and during the day it swims toward the sun. These instinctive behaviors deliver the larva to the surface, where it comes within reach of the wind. The larva slides along with the topmost layer of water, skimming the sea with the breeze.

  But the larva’s foray at the surface is short-lived. After several days the first-stage larva sheds its shell and enters a second stage, which is more sophisticated. It has grown only a millimeter but it has gained new appendages and muscles. It floats below the surface, perhaps ten feet under or even deeper, putting it at the mercy of the gulf’s complex currents. Soon it molts again and becomes a third-stage larva. It remains low in the water, continuing to travel with the currents. By now it has developed many of the characteristics of a lobster, including tiny claws, swimmerets, and tail flippers. Finally it becomes a postlarva, or superlobster, and returns to the surface to swim and sail on the wind. After a few days the superlobster begins to dive, searching for cobblestones in shallow water.

  Lew Incze’s specialty was larval ecology, and he knew that it could take a lobster larva anywhere from twenty to forty days, sometimes even longer, to develop from a hatchling on its mother’s tail to a baby bedded down in a nursery. Given the way wind and water moved in the gulf, that was enough time for a larva to travel quite a distance. Lew teamed up with a physical oceanographer who combined AVHRR satellite readings and other data with a state-of-the-art circulation model running on a computer. The model would divide the gulf into thousands of three-dimensional triangles and compute the effects of tidal transport, temperature, salinity, and turbulence, along with the gulf’s dominating counterclockwise gyre. Lew could then track individual particles moving inside the flow field.

  Lew integrated a biological model of the lobster’s larval life cycle into his colleague’s physical model of the ocean. Coupling biology to physics was a delicate art. The biological model had to simulate an individual larva hatching and then developing through all three larval stages prior to the superlobster stage. Lew could then assign a hatching location to a hypothetical larva and run the biological model inside the physical model to see where the larva ended up in the ocean when it was ready to become a superlobster. Alternatively, Lew could run the model backward. He could assign an arrival location for the larva and, as if he were pressing Rewind on a video, tell the computer to run the currents in reverse to calculate where the larva might have hatched.

  Using this reverse method, Lew chose a series of end points around the Pemaquid region of Maine’s western coast, indicating where the hypothetical larvae had arrived. By running the model backward, he might get an idea of where the superlobsters that he and Rick had been counting for the past decade had been coming from.

  For some of his arrival locations, Lew selected the coastal nurseries. But it was possible that superlobsters also arrived from farther offshore. The physical model indicated that even a weak onshore breeze could propel a superlobster into the nurseries from fifteen or twenty miles out. So in addition to the arrival locations near shore, Lew selected a string of locations that were between fifteen and twenty miles out to sea.

  When Lew ran the model backward, the computer drew a series of white lines onto a map of the Maine coast, leading back in the direction from whence the currents would have come. Each line covered a series of upstream locations where the virtual larva could originally have hatched from under its mother’s tail.

  The results fell into two rough categories—larvae that traveled short distances and larvae that came from farther away. The computer calculated that some of the larvae in the nurseries had probably hatched nearby, the white lines forming short squiggles that corresponded to local currents. That made sense. Female lobsters that stayed in shallow water might not be exposed to the larger currents in the gulf, and their offspring wouldn’t have traveled far. Lew supposed that local larvae, traveling short distances close to shore, might account for much of the settlement in the nurseries in the central and western half of the Maine coast.

  But for the larvae that Lew had programmed to sail into the nurseries from offshore, the white lines that the computer drew looked quite different. They weren’t short squiggles. They were long-distance highways. They stretched up the coast for a hundred miles or more, the hatching locations well into eastern Maine and beyond. These virtual larvae were riding the Gulf of Maine’s counterclockwise gyre down the coast, rafting the powerful rapids of the Eastern Maine Coastal Current.

  Lew suspected that each of these highways had on-ramps along its entire length, with larvae joining the traffic from any number of locations off Nova Scotia, the Bay of Fundy, and Down East Maine. It was possible that the delivery of larvae over long distances had helped fuel the increase in catches along the western half of the Maine coast during the 1990s.

  To the extent that long-distance larvae might have supplemented local larvae in western Maine, Lew thought it likely that they had come from a variety of locations throughout the northwest gulf. All the same, during the computer’s rudimentary simulation it was remarkable how many of the white lines converged in the vicinity of a single large island just over the Canadian border called Grand Manan.

  Dan and Katy Fernald’s daughter Erin loved Wellesley College, but she also loved Little Cranberry Island. Dan and Katy had faced some opprobrium for pushing Erin to seek a highbrow education, but now Erin enjoyed the best of both worlds. As her sophomore year at Wellesley drew to a close in the spring of 2001, she knew she would miss the stimulation of attending classes, but she was looking forward to returning to the island to work in her parents’ art gallery for the summer.

  But she wasn’t going anywhere until she wrote her term paper for Econ. 228—Environmental Economics. Erin had grown up listening to her dad, her uncles, and Jack complain about the government’s approach to managing the lobster fishery. She’d also heard stories about her mother’s college thesis on the economics of lobstering. Now that Erin had the resources of a world-class educational institution at her disposal, she thought it m
ight be time to form her own opinion.

  The term paper had been assigned as a team project. Erin broached the idea of writing about lobsters to her team partner, a student from California, and was surprised when she readily agreed. A string of long nights in the library resulted in a twenty-page monograph titled “Resource Allocation and Regulation of a Common Pool Resource: The Lobster Industry of Maine.”

  On the last page of the paper, Erin and her classmate wrote that “managing a fishery is a complex process, involving economics, biology, and the study of the social climate of the fishermen themselves.” Having grown up on Little Cranberry Island, Erin thought she had a handle on the social climate part. Economics too made more sense after taking the class and researching the paper. But she was still curious about biology. Before leaving for summer vacation, Erin decided to sign up for a biology class when she returned to campus in the fall. She had been thinking of declaring a major in one of the sciences.

  Back on the island, Jack Merrill got wind of Erin’s new interest in lobster biology and mentioned that Bob Steneck was planning another research cruise to study lobsters. He would be passing right by Little Cranberry.

  A week later Erin was standing on the deck of the R/V Connecticut, where she was introduced to Bob and his crew. She also made the acquaintance of the Phantom, the underwater robot that was Bob’s latest tool in his quest for large lobsters. Now that he had scoped out the seafloor using the Johnson Sea-Link manned submersible, he could conduct quicker and cheaper follow-up surveys with remotely operated vehicles—ROVs—like the Phantom.

  Erin’s workday aboard the Connecticut began at 7:00 A.M. and continued at a frenetic pace until eight or nine each night. The Phantom completed five dives a day, generating an hour of videotape on each dive. During the dives, two research assistants sat in the darkened control room, glued to the Phantom’s live video feed from the ocean floor. One assistant typed commands into a computer that controlled the zoom angle on the Phantom’s camera while the other recorded depth, temperature, and time. After each dive a third assistant reviewed the videotape in the Connecticut’s lab. Each time a lobster appeared, the assistant hit Pause and gauged the lobster’s size by the distance between the red dots projected by the Phantom’s lasers. An hour-long dive might uncover as many as forty lobsters.

  Erin performed all of these tasks and learned to sleep next to the roar of the ship’s 800-horsepower engine. The Connecticut operated twenty-four hours a day. Before Erin and the other dive assistants bedded down each night, their bunks were vacated by the Connecticut’s second shift. The night crew included a graduate student of Bob’s who was working with Lew Incze on lobster larvae. From dusk till dawn he towed a fine mesh net behind the Connecticut at a variety of depths. In the morning Erin would open the refrigerator in the lab to find vials of somersaulting lobster larvae and superlobsters tapping at the walls of their containers.

  Half the fun of the cruise for Erin was listening to Bob talk. In the darkened control room, with mud and rocks passing across the video screen as the researchers waited to find the next lobster, Bob would sip from his fifth or sixth cup of coffee and pontificate on evolutionary theory, phylogenetic classification, and the philosophy of science.

  “I was thinking of maybe majoring in geology,” Erin told Bob.

  “Hey, that’s what I majored in!” Bob exclaimed. “Actually, geology and biology—a double major. You should!”

  As the Phantom traversed the Gulf of Maine, Erin saw all manner of sea life, including flounder, hake, cod, and ocean pout, along with baby octopuses, orange sea anemones, patchwork fields of black and blue sand dollars, and intricate coral formations. One day the Phantom even found a shipwreck. One night the Connecticut sailed through a migration of bats. Erin woke to find the winged mammals flying around inside the ship.

  When the Connecticut passed into Canadian waters, Erin witnessed the one thing she most wished her father, her uncles, Jack, and every other lobsterman on Little Cranberry could behold—the seafloor off the island of Grand Manan. At the mouth of the Bay of Fundy, where the highest tides in the world rose and fell twice a day, the Phantom was lowered off the stern, and Bob gathered his crew around the video monitors in the command module.

  “This,” Bob said, “you have got to see.”

  The Phantom descended, and in a few minutes Erin could make out a murky plain of mud. The Phantom had gone only a short distance when a circular depression appeared, a dish five feet wide. Hunkered in the center was the biggest lobster Erin had ever seen. It was a female, at least two feet long, and from her tail hung perhaps a hundred thousand eggs. A few yards beyond was another pit with another mammoth mother, eggs bursting from under her tail. After that there was another, and after that, yet another. The bottom off Grand Manan was a vast expanse of egg-bearing lobster dens, one of the greatest aggregations of fecund females that had been found in the Gulf of Maine.

  While Bob Steneck stalked females Down East with his underwater robot, Diane Cowan was clambering aboard lobster boats in the western half of the Maine coast with different technology. Her tools for stalking female lobsters were tubes of superglue and rolls of olive-drab duct tape. She also carried with her a container of yellow disks, each the size of a wristwatch, and a tray of solid white rods that looked like glue sticks.

  Since founding the Lobster Conservancy, Diane had continued to count baby lobsters fourteen times a year at low tide with a zeal that verged on the religious. Local newspapers now referred to her as the Jane Goodall of lobsters, and the local lobstermen had come to expect her in the mud at water’s edge at 5:00 A.M. or 6:00 P.M. or God knew what other hour. Soon the lobstermen were looking out for Diane like a friend, and they joked with her the way they joked with each other.

  “How long you been turning over rocks looking for them baby lobsters, anyhow?” one fisherman asked.

  Diane had to think for a second. “I guess it’s been nine years.”

  “Nine years?” He laughed. “Jeez, you ain’t as smart as I thought you were, are you?”

  Diane had recently been hired as the state of Maine’s chief lobster biologist, but astonishingly, even that job had presented the same problem as some of the teaching jobs she’d tried—too much time in an office, not enough time with the lobsters. So she’d quit.

  Now she was living on an island with a winter population of three, in a small house overlooking an old lobster pound that had been donated to the conservancy. Backed by acres of woods, the house sat on a windswept ledge by the ocean. Her electricity came from solar panels and her heat from a wood stove. For half the year she hauled her water from an outdoor well. She’d relinquished day-to-day management of the conservancy to a staff on the mainland, who now oversaw eighty volunteers sampling baby lobsters at thirty sites around New England, including Little Cranberry Island.

  Free again to focus on research, Diane hoped to use the cordoned-off cove that formed the old pound to rekindle her first love, the study of lobster sex. Her plan was to outfit the bottom of the cove with lobster homes spacious enough for two, rig up an underwater video surveillance system, and populate the cove with the largest male and female lobsters she could find.

  In the meantime, Diane had devised a project to help answer the crucial question of where lobster larvae were hatching in the wild. While Bob Steneck and other scientists studied egg-producing lobsters in deep water using submersibles, ROVs, and other tools, Diane convinced fourteen of her fishermen friends to help her follow female lobsters in waters closer to shore.

  On a typical autumn day Diane boarded a lobster boat at 5:00 A.M., her bag loaded with her collection of specialized equipment. When the fisherman hauled up an egg-bearing lobster, Diane noted the developmental state of the eggs and recorded the lobster’s location using a GPS receiver. That was one way to determine where a female lobster might hatch her spawn. Another was to attach a homing beacon to the lobster’s shell and track her.

  Aboard the fishing boats, Diane deft
ly refashioned nearly two hundred new mothers. After drying an egger’s back with a towel she wove a strip of duct tape—olive-drab to match the lobster’s natural camouflage—through her fingers and squirted on three lines of superglue. Then she picked up one of her white rods, laid it on the center line of glue, wrapped the edges of the tape down around the rod to create a pair of sticky flaps, and attached the device to the lobster’s back. The rod was a sonar transmitter that would emit a unique sequence of beeps for the next twelve months.

  Next she tied a plastic bracelet around the narrow wrist behind the lobster’s claw and attached one of her wristwatch-sized yellow disks. The disk was an automated thermometer that would record water temperature every hour for up to four years. Ready to go overboard, the lobster looked like a muscle-bound scuba aficionado just back from the dive shop—new tank on her back, snazzy yellow sports chronometer bulging on her bicep.

  The fourteen lobstermen outfitted their fishing boats with hydrophones that could detect each female’s sonar signal from half a mile away. While hauling traps, the fishermen, even if they never caught the lobsters again, could listen for them under the waves. Diane equipped her own open-decked skiff with hydrophones and motored into the bay at every opportunity to listen for her mothers through her headphones, each lobster clicking away on the bottom with one of thirty numeric codes on one of ten different frequencies.