In the western cove of Damariscove Island on that gray November day, Rick Wahle had lifted more stones off the bottom and discovered more tiny lobsters, but he’d also discovered a problem. When he disturbed the stones a cloud of sediment obscured his view. It was obvious that the cove was a nursery for lobster babies, but with clouds of silt everywhere, it was difficult for Rick to get an accurate estimate of their numbers.
Recalling his days vacuuming up algae and worms near the Seabrook nuclear power station nearly a decade earlier, Rick returned to Bob Steneck’s lab and rummaged through a pile of unused sections of PVC pipe, but none were quite right. A trip to the hardware store secured what Rick wanted—a section of wide plastic pipe three feet long, along with several sheets of flexible window screening. Rick drilled a hole near one end of the pipe and attached a flexible hose, running the other end of the hose to an old scuba regulator on a tank of compressed air. He folded the window screening into a bag and strapped it over the other end of the pipe, then stood back to admire his handiwork. It looked like a makeshift bazooka.
The following summer Rick and an intern piloted their skiff back out to Damariscove Island’s western cove, this time carrying Rick’s underwater vacuuming device. They slipped the contraption into the water and swam with it down to the cobblestone floor fifteen feet below the surface. Similar devices—called suction samplers or airlift samplers—were commonly used to collect things like clams as well as algae and worms, and using one to collect baby lobsters seemed like a reasonable idea. But Rick wasn’t sure it would work.
Holding the pipe upright, Rick twisted open the valve on the tank. A stream of bubbles shot through the hole and rose the length of the pipe before bursting out through the mesh bag at the top. Rick gave his intern a thumbs-up, then lowered the pipe while the intern lifted stones out of the way. The stream of air generated a suction that inhaled everything into the pipe in a blur. When Rick closed the regulator valve and detached the mesh bag, the sand and silt had mostly blown through the mesh and away from the divers. What remained inside was a collection of shell hash, pebbles, and baby lobsters.
After making some modifications to his suction sampler, Rick was ready to put it to use. He first searched for other nurseries over a ten-mile swath of coastal sea. Between Damariscove Island, which lay exposed five miles offshore, and Pemaquid Harbor, an estuary five miles inside a narrow bay, Rick chose five locations. Each contained three kinds of underwater terrain in close proximity—open bedrock, sediment, and cobble.
Rick had read Stan Cobb’s papers on superlobsters—the little postlarvae that swam to the bottom and transformed themselves into the babies Rick was studying. If Maine’s superlobsters were like the ones Stan had studied in dishpans, they would avoid both the open bedrock and the less protective sediment. Instead, they would seek out hiding places among the nooks and crannies in the cobble—and there they would stay, molting to become babies. With assistance from Bob and a team of student divers, Rick set out in the summer of 1988 to fulfill his role as an ecologist by mapping the patterns of distribution and abundance of the natural world.
At each site, Rick and his divers began by throwing down a square frame made of rebar, a half meter on a side and spray-painted orange, called a quadrat. By delineating random pieces of bottom that were always exactly the same size, the quadrat helped the divers generate statistically useful data from which they could extrapolate.
When working on cobble, the divers removed the stones inside the quadrat while suctioning away the silt underneath. On mud bottom, the divers suctioned six inches of surface layer away because baby lobsters had been known to drill U-shaped tubes when the mud was deep enough. Sand was too loose for burrowing, so there the divers didn’t bother with suctioning but compiled their censuses by sight, as they did for solid bedrock. In a matter of weeks, Rick and his team had sampled more than 350 quadrats and blown through some 120 tanks of air.
The pattern was astonishingly clear. Superlobsters settled, and baby lobsters lived, almost exclusively in shallow coastal seafloor where more than two-thirds of the bottom was composed of cobblestones at least several inches in diameter. Bedrock and sediment were mostly bare of babies.
But the seafloor along the Maine coast was mostly bedrock and sediment. Rick calculated that only about 10 percent of the bottom in his study area contained the kind of prime cobble that baby lobsters required. If the rest of the Maine coast was similar, then the terrain of the seafloor itself might well be the bottleneck that limited the lobster population.
That made the bottleneck almost impossibly tight. Yet there was evidence that something made it even tighter. Even when prime cobble was present it could lie barren. Why, for instance, on the eerie island of Damariscove, was the cobble cove facing west home to more babies than anywhere else, while the cobble cove facing east was home to little but ghosts?
Catching insects with a butterfly net hanging off a helicopter might have been easier. Lewis Incze, an oceanographer at the Bigelow Laboratory for Ocean Sciences, was an expert at catching the larvae of crustaceans, and he’d offered to use his remarkable skills to help Rick Wahle unravel the mystery of Damariscove Island. While Rick counted babies on the bottom, Lew searched for superlobsters on the surface.
Lew stole a glance at the sea ahead, then returned his gaze to the net skimming along the water from a boom off the side of the boat. The tiny holes in the net’s one-millimeter mesh barely let through water, let alone superlobsters, and Lew had to make sure a floating log or tangle of seaweed didn’t tear the net. A rectangular frame at the mouth of the net was attached to a pair of miniature water skis, which kept the lower edge of the opening at a depth of half a meter. If there were superlobsters swimming at the surface, Lew’s net ought to snag them.
The boat was running west in a line straight from Damariscove Island. At the end of the tow Lew hauled in the net and dumped out the contents into a sorting tray. A research assistant helped Lew comb through the pile of debris, seaweed, and plankton while the boat’s captain steered toward the beginning of the next tow. With the height of the superlobster season upon them—it was the middle of August—the researchers were repeating this routine sixty to seventy times a day.
Lew liked being on the water. He was an avid sailor, and his office at the Bigelow Laboratory in Boothbay Harbor was just a twenty-minute cruise from Damariscove Island. Lew had grown up in Maine and from the age of five had spent his summers living on a tiny island with a single cabin. His graduate work had taken him to the opposite edge of the continent, where he’d earned a Ph.D. chasing the larvae of Alaskan snow crabs through the Arctic climes of the Bering Sea. He was glad to be back in his old neighborhood, because the Gulf of Maine was a unique natural laboratory for the study of oceanography. Whether Lew was at work on a research cruise or enjoying a summer sail, the gulf’s constant movement intrigued him—its cold deep currents, its warm shallow eddies, its turbulent upwellings, its prevailing winds. The question of how the physics of the sea interacted with the biology of its creatures fascinated him.
After the last tow on the western side of Damariscove Island the captain gunned the boat for the mile-long trip around the island to the eastern side. The afternoon sun had kicked up a breeze out of the southwest, a trademark of the Maine coast in summer, and the boat wobbled on the fluttering sea. Lew had yet to analyze the numbers, but so far he’d seen an obvious pattern. On his offshore tows, Lew had been catching similar numbers of superlobsters whether he was on the east or west side of the island. That wasn’t the case near shore. When he trolled over the western cobblestone cove where Rick’s nursery lay, Lew caught superlobsters in numbers that often exceeded his catches offshore. But above the cobblestone cove on the eastern side, Lew’s net usually came up empty.
To a sailor like Lew, who’d spent his boyhood on the coast, the puzzle wasn’t difficult to solve. Lew compared his data with wind readings from a weather buoy anchored near Damariscove and saw that the direction of the s
ummer breeze easily accounted for the patterns he and Rick observed. Damariscove Island’s narrow, north-south profile ran nearly perpendicular to Maine’s east-west coastline. The southwesterly wind was pushing the surface water containing superlobsters up against Damariscove’s western edge. At the same time, it blew across the island’s narrow waist and pushed surface water away from the eastern edge.
Combined with the effects of tidal currents around the island, the southwesterly breeze was creating a superlobster hot spot on one side and a corresponding shadow on the other, despite the presence of hospitable cobble in both places. Most likely, similar effects had been in play when the beheaded ship captain and his ill-fated dog had washed ashore three centuries before.
Given how common the southwesterly breeze was along the Maine coast, it seemed likely that cobble facing east would almost always catch fewer superlobsters than cobble facing west. The effect would be an even narrower demographic bottleneck than could be accounted for by the terrain of the bottom alone. Back at the Darling Marine Center, Rick Wahle chanted Bob Steneck’s mantra of ecology to himself—patterns, processes, mechanisms—and contemplated the picture that was emerging.
The pattern was obvious. Baby lobsters were concentrated in cobble, particularly in coves facing the prevailing southwest breezes of summer. The general processes responsible for that pattern were becoming clear. Water movements delivered postlarvae against western shores, and then the little superlobsters swam to the bottom and, if they found cobble, molted to become bottom-dwelling babies. The mechanisms behind the processes were more specific—the physics of wind-forcing on surface water, for example, and the navigational and shelter-seeking behaviors that were hardwired into the superlobster’s nervous system.
But to understand the behavior of superlobsters Rick had to think not in minutes, hours, or days, but, as Bob had taught him, in hundreds, thousands, or even millions of years. The process of evolution had selected some superlobsters over others, favoring the behavioral traits in evidence today. Superlobsters carrying a genetic code that instructed them to find hiding places immediately had survived and passed on their genes. The rest had died. Why?
The ecological training Bob had given Rick had included the unpleasant lesson that evolution was as often a matter of death as of survival. It wasn’t long before Rick discovered the gruesome fate awaiting baby lobsters that never found the nursery grounds.
11
Attack of the Killer Fish
Warren Fernald gaffed his next white-and-yellow buoy and tapped the throttle of the Mother Ann down to idle. He spun the wheel to port so the boat would drift in a circle back toward the trap and take the strain off the rope, then tugged up a few feet of line and flipped the slack over the hauler pulley. He pushed the lever on the bulkhead that powered up the hydraulic hauler and threaded the rope between the spinning steel plates. The hauler whined, tightened the line, and reeled it in.
Warren allowed his eyes to wander over Little Cranberry Island in the distance. Before shifting his gaze back to the rope, Warren glanced over his shoulder to check on his son Dan, who was hauling traps nearby in the Wind Song. As a precaution, the Little Cranberry fishermen kept an eye on one another.
Warren had learned the hard way how easily a lobsterman could find himself near death. One winter afternoon he was fishing without a sternman. He threw his last trap of the day overboard when a nail protruding from the trap caught his glove and dragged him to the transom. His boots left the deck and he was about to tumble over the stern when the glove came off. Head and shoulders over the water, he had lain there and watched the white shape of a hand sink out of sight.
Another day Warren had thrown a pair of traps off the rail and gunned his engine, only to see that he’d stepped inside a loop of buoy line. The rope pulled tight around his ankle and dragged him aft, away from his engine controls. He dived to the deck, lodged himself under the stern, and wrapped his arms around the mast of his riding sail while the boat raced out of control. As the boat dragged the two traps through the waves, the rope cut into Warren’s ankle. In moments the force would pull him overboard. He let go of the mast with one hand and fumbled in his pocket for his jackknife. Opening the knife with his teeth he sawed frantically at the rope until tendrils of twine splayed with the strain and then, with a pop, finally the rope parted. He’d lost his traps but not his life.
Warren stole another glance at Dan. Every parent worried about the safety of his or her children, and perhaps no one more than a commercial fisherman who counted three fishermen among his sons. Warren had to hope that his boys would never come as close to a grisly death on the water as he had. Given the history of Little Cranberry, though, such hopes might be hard to fulfill. The sons of the island had been dying at sea for nearly two centuries.
Before lobsters were worth trapping, fishermen from Little Cranberry Island perished in pursuit of another catch—the cod. Little Cranberry was probably settled around 1762, but the craze to catch cod didn’t arrive on the island until 1803, when a man named Samuel Hadlock anchored his ninety-ton schooner, Ocean, in the harbor. Hadlock had encountered a streak of bad luck on Mount Desert Island. His house had burned to the ground, he’d sunk two boats, and his father had just been hanged for murder. Moving to Little Cranberry offered a fresh start.
To restore his fortunes Sam hired a crew of local men and sailed for the Grand Banks, a thousand miles away. Sam’s luck improved and he filled his hold with fish. He dried them on the shore of Labrador and sailed east, running French and British blockades to sell his catch in Portugal at premium prices. After a trading run to the Caribbean, Sam returned to Little Cranberry a rich man. He bought a fleet of schooners and transformed the little island into a hub of the New England cod trade. At any one time, six hundred ships might be seen in the waters around the Cranberries and Mount Desert.
But the price of prosperity was steep, for catching cod offshore was dangerous work. Almost every family on Little Cranberry Island sacrificed sons to the deep. Sam in particular paid in proportion to his wealth. By the time he died at the age of eighty-four, three more of his ships had sunk and four of his five sons had died at sea. Cod stocks in the western North Atlantic dwindled, and on Little Cranberry Island, the Hadlock dynasty had waned, making way for a new dynasty built on lobsters. By the late twentieth century, the Fernald family had risen to ascendance.
Aboard the Mother Ann, Warren finished cleaning out his trap and shoved it overboard. As the buoy line played out over the stern, he steered his boat toward the white hull of the Wind Song to greet his son. When Warren pulled alongside, Dan had just gaffed another buoy and was slipping the rope through the heavy steel housing of his hauler pulley. He wound the rope into the sheaves of the hauler and started it spinning before turning his attention to his father. Warren had gotten a couple of words out of his mouth when Dan’s rope went taut. There was a crack like a rifle shot and the pulley housing leaped from its mount and slammed into Dan’s jaw, knocking him across the boat and onto the deck, where he lay inert, limbs splayed at awkward angles.
“Dan!” Warren shouted.
A full minute passed without a sign of life. Warren maneuvered the Mother Ann toward the side of the Wind Song so he could lash the boats together. He saw Dan regain consciousness, his head battered but intact. Another close call.
Hunched over his lab bench at the Darling Marine Center, Rick Wahle held another baby lobster on the tip of his thumb. Squinting, he used a pair of calipers to measure the length of the animal’s carapace—six millimeters. Rick put down the calipers and lifted a piece of fine nylon thread. He’d tied a loop the size of a pinhead in one end of the line. He dipped the loop into a dish of superglue. A tiny drop of the glue stuck to the thread. After blow-drying the moisture off the lobster’s back, Rick touched the drop of glue on the thread to the top of the lobster’s carapace. It adhered instantly.
Rick sat back in his chair, took a deep breath, and expelled the air from his lungs. Rolling his
head to stretch the muscles in his neck, he wondered how he had ever come up with the idea of putting a baby lobster on a leash, let alone doing it to over two hundred specimens.
Stanley Cobb’s experiments had shown that when a superlobster’s biological clock ran out of time, it would swim down and molt into a bottom-dwelling baby even when all it could find was open bedrock or bare sediment. If this happened in the wild and the lobsters survived anyway, then Rick’s hypothesis that baby lobsters required cobble would be wrong. But if they failed to survive, then Rick would have found additional evidence of the demographic bottleneck. Only baby lobsters hiding in a cobble nursery would live. Those that failed to find cobble would die.
The fine nylon thread and superglue worked only on the smallest lobsters. On his one-and two-year-old babies Rick tied a piece of braided fishing line snug around the animal’s carapace like a belt and attached a steel fishing leader. The lobsters would reach down and grab the leader with their claws, but they couldn’t break the metal. Rick dangled each animal in the air on its leash and bounced it up and down a few times to ensure that the tether was secure before dropping the baby lobster in its own private dish.
Borrowing Bob Steneck’s leaky houseboat, Rick took a summer intern from the lab and moored the boat in the bay. Rick and his assistant splashed overboard, spread patio tiles out at intervals of a few feet, then returned to the boat. Rick had sorted his pretethered baby lobsters into three size categories. With the lobsters in bags, they dove again and clipped each lobster’s leash to a tile. Once in place, the lobsters scurried frantically about their individual patios, but like a puppy tied to a stake, each lobster hit the end of its tether before it could run away.
The Secret Life of Lobsters Page 15