Sunset on the Maine coast from the deck of the schooner Victory Chimes, with one of the ship’s small dories and another sailboat on the horizon.
Credit: Mary Caperton Morton

Riddled by inlets, bays, and estuaries, Maine’s famously convoluted coastline is actually longer than California’s. But don’t expect long walks on the beach; less than 2% of the state’s 5,598-kilometer-long coastline is sandy, the rest being dominated by rocky headlands or tidal inlets. This ragged edge has always been difficult to travel by land, and Mainers have long made their living from the sea.

A bird’s-eye view of the central Maine coast, including Mount Desert Island, the two-lobed island at center right, home of Acadia National Park. Credit: NASA

In the face of rising sea levels, Maine’s rugged seaboard will likely fare better than most, but climate change is hitting harder offshore: The Gulf of Maine is warming faster than the rest of the Atlantic Ocean, affecting the entire food web, from plankton to cod to right whales, along with the fishing industry. In the geologic future, the rocky coast of Maine may look more or less the same, but the gulf may become home to a very different array of fish.

Only the Strongest Survive

On the mostly flat and sandy eastern seaboard of the United States, Maine stands out as a rocky anomaly. “Maine is famous for its rockbound coast,” said Joseph Kelley, a marine geologist at the Maine Geological Survey. “The rocks here are almost fixed features; they don’t erode much.”

On human timescales, Maine’s seaside rocks seem abiding, but a lot has happened to them in 550 million years. Maine’s coastal geologic history is an epic saga of ancient oceans, island collisions, volcanism, seafloor sediments, and metamorphism that produced an impressive array of highly erosion resistant rocks.

Coarse-grained pink granite cliffs looming above the ocean make for a dramatic setting for rock climbing in Acadia National Park. Credit: Leigh Frye/Erika Sweeney

These granites, marbles, gneisses, and schists have been sculpted by the breakup and formation of several continents and ocean basins, multiple uplifts of the Appalachian mountain chain, and the last glacial period, when the Laurentide Ice Sheet advanced more than 450 kilometers offshore to the edge of the continental shelf.

At the end of the last ice age, the ice sheet retreated, revealing a complex coastline dotted with thousands of islands, ranging from the size of a baseball diamond to the 280-square-kilometer Mount Desert Island, home of Acadia National Park. Today around 3,500 islands rise above the waves, hinting at the much larger bedrock features hidden beneath the surface. In the past, when sea levels were as much as 55 meters lower, thousands more islands and peninsulas may have existed, now drowned by the rising sea.

The Original Mainers: People of the Dawnland

People have been making a living along Maine’s rocky coast for at least 13,000 years. Native Americans from the Abenaki, Maliseet, Micmac, Passamaquoddy, and Penobscot tribes, collectively called the Wabanaki, meaning “People of the Dawnland,” have long thrived off the bounty of the sea. Maine’s earliest residents were skilled canoeists, plying their dugout and birchbark crafts down rivers, across bays, and between islands.

“In Maine, before the advent of highway and railway bridges, overland travel was difficult. You can’t go very far before you hit a lake, pond, river, stream, estuary, or some kind of wetland,” said William Haviland, an anthropologist at the University of Vermont. “So water transport was the most efficient way to get around.”

This birchbark canoe was made by the Wabanaki Peoples sometime between 1720 and 1780 and may be the oldest such canoe in existence. Credit: Paul VanDerWerf/Wikimedia, CC BY 2.0

Birchbark canoes, thought to have been invented around 3,000 years ago, were “the equivalent of today’s pickup trucks,” tough enough for ferrying loads across open water but also light enough to be portaged between waterways, Haviland said. Indigenous Peoples are known to have paddled throughout Maine’s many islands and all the way out to Matinicus Isle, a small group of islands 32 kilometers off the mainland, whose name means “far out islands” in Abenaki.

Skilled fisherfolk used hooks, nets, and weirs and hunted more formidable prey such as swordfish and porpoises with spears from both dugout and birchbark canoes. When the first European explorers reached the northeastern coast in the 1500s, they reported an astonishing abundance of fish. According to legend, cod were once so plentiful a person could walk on water across the backs of the hefty 32-kilogram (70-pound) fish. But the bounty would not last. In less than 500 years, people would pursue the once prodigious cod to the edge of extinction.

Windjamming in an Island Paradise

Of all the bays in the world, Maine’s island-packed Penobscot Bay may be the best possible place for windjamming. Windjamming is the nautical equivalent of city slickers playing cowboy on a dude ranch; aboard a commercial sailboat, novice mariners learn to sail the old-fashioned way by hauling ropes, hoisting sails, and following the wind.

On a windjammer cruise, passengers are called to help raise the sails. Credit: Mary Caperton Morton

The picturesque Penobscot Bay harbor towns of Rockland and Camden both host a fleet of windjammer sailing ships. The largest and arguably most famous of these historical wooden ships is the Victory Chimes: The 39-meter-long, three-masted schooner is the last still-sailing vessel of its kind, and its likeness appears on the Maine quarter. So when my brother’s Celtic/Americana folk band, the Chivalrous Crickets, was hired as the onboard entertainment on a 6-day musical cruise aboard the Chimes, my sister and I jumped at the chance to live out our windjamming dreams.

Today the Victory Chimes is a rare creature, but when it was built in 1900, the shipbuilding industry was churning out dozens of huge wooden ships each year for moving cargo up and down the East Coast (the Chimes was retrofitted to carry passengers in 1946).

When I complimented Capt. Sam Sikkema on how beautifully maintained the Chimes is for a 121-year old ship, he told me, “We have to take good care of her. If we had to replace certain parts of her, like the masts, we wouldn’t be able to harvest the trees to do it.” The Chimes’s three masts are all more than 24 meters high, made from Douglas fir trees shipped from Oregon. To replace a mast that tall, the original tree must be perfectly straight for 33 meters of height, with a diameter greater than 53 centimeters. “There aren’t that many trees left that big, and the ones that do exist and are usually protected,” he said.

Victory Chimes is the last still-sailing ship of its kind. Credit: Mary Caperton Morton

Penobscot Bay, a major inlet of the Gulf of Maine, is dotted with hundreds of islands that create endless passageways and safe harbors to explore, with typically smooth seas and steady wind currents. When we set sail out of Rockland, not even our captain knew exactly where we were going or how we would get there.

“We have a wide-ranging territory at our whim, and our itinerary is most often set by the wind and tides,” said the ship’s photographer, Quentin Donleavy. “Some trips have set stops included, but even then, how we get there and how we get back is a wonderfully free flowing adventure.”

Each evening, Capt. Sam Sikkema would draw out the day’s route on a map of Penobscot Bay. This was our route by day 4. Credit: Mary Caperton Morton

On our 6-day cruise, we sailed across West Penobscot Bay, north of North Haven Island, through Eggemoggin Reach, under the Deer Isle Bridge (with mere centimeters to spare between our 24-meter masts and the 25-meter-high bridge), back and forth across Jericho Bay, south of Deer Isle, and then east across East Penobscot Bay back to Rockland.

Each day of the trip the crew rowed us ashore in small boats to explore a small port town or uninhabited island, and each evening the Crickets filled an otherwise quiet cove with sea shanty sing-alongs. At night the Milky Way was so bright that I abandoned my tiny bunk bed berth in favor of sleeping on the deck under the stars. Never mind that I awakened each morning soaked in dew.

Cod Coda, End of an Ecologic and Economic Era

On the surface, skimming across Penobscot Bay on an engineless wooden sailboat felt much the same as it might have 100 years ago. Even our crew sported historical clothing and drank out of green glass bottles. But under the waves, the Gulf of Maine is undeniably changing. Studies have shown that the 93,000-square-kilometer bay is warming as much as 7 times faster than the rest of the world’s oceans.

In the past 15 years, the Gulf of Maine has warmed at 7 times the global average, faster than 99% of the ocean. Credit: NASA

Sandwiched between Cape Cod and Nova Scotia, the Gulf of Maine sits right at the boundary where the colder waters of the North Atlantic meet the warmer waters of the Gulf Stream, said Andrew Pershing, director of climate science at Climate Central and a former ​​chief scientific officer for the Gulf of Maine Research Institute.

As the planet and its oceans warm, increased melting of Greenland’s ice has disrupted the saline balance of the cold-water Labrador Current, lessening its influence on the Gulf of Maine. Meanwhile, the warmer Gulf Stream is shifting north. “It’s kind of like having a warm tap and cold tap in a bathtub,” Pershing said. “For the last decade or so the warm tap has been cranked up, and the cold tap has been turned down.”

The gulf’s water-trapping C shape and relatively shallow depth exacerbate this warming trend, creating a natural laboratory that demonstrates what happens to subpolar marine life as we turn up the thermostat. “Every fish population is going to have a range of temperatures where it thrives,” Pershing said. “A lot of the classic species in the Gulf of Maine are subpolar species on the southern edge of their range, and as the gulf has warmed up, we’re seeing those subpolar species be stressed in various ways.”

Perhaps the most famously affected population is the Atlantic cod. With its mild, flaky flavor, perfect for fish-and-chips, cod has been the backbone of the New England fishing industry for 500 years. “Cod are such an iconic species. They’ve been the economic driver for fishing communities in Maine and Massachusetts for a long, long time,” Pershing said. In their ecosystem-dominating heyday, cod had an estimated biomass of several million metric tons, with commercial fishermen harvesting between 200,000 and 400,000 metric tons each year.

The cod fishery in Vinalhaven, Maine, brought in tons of fish to dry (front) and salt (back) in 1936. Credit: Richard/Flickr, CC BY 2.0

After peaking in the 1960s and 1970s, the annual cod catch began to decline, despite advances in fish-finding technologies like radar and sonar. But regulatory agencies were slow to recognize that the once seemingly bottomless cod population was approaching collapse. By the time the Canadian government abruptly banned cod fishing on 2 July 1992, the northern cod population had crashed to mere tens of thousands of metric tons, less than 1% of historic levels.

Overfishing is the most obvious culprit in the cod’s downfall, but the warming ocean is also an accomplice. “In warmer waters, female cod produce fewer babies than we would expect, and we also see that the young fish are less likely to survive and become adults,” said Pershing. Some fishermen also point to larger numbers of predators that eat cod, like dogfish and gray seals.

In the past decade, U.S. fishing regulations have tightened to protect the remaining cod population from commercial fishing, but “cod are not keeping pace with management’s goals for rebuilding,” said Lisa Kerr, director of the Quantitative Fisheries Research Lab at the Gulf of Maine Research Institute.

“Going forward, we will need to adapt and start thinking about sustainable ways of harvesting new species. In 50–100 years, I think we can expect that it will be a whole new fishery.”

“Currently, cod are only at about 5% of their target biomass,” Kerr said. “It’s becoming clear that we need to reset our expectations for what recovery means. Right now our target is quite high because it’s based on our historical understanding of cod productivity. But we are shooting for conditions that no longer exist,” she said. “I think going forward we will need to grapple with whether there should be a new target for what constitutes a rebuilt cod stock, given what we’re learning about how productive they can be in this new, warmer ocean.”

Other species, including haddock, pollock, redfish, and lobster, are faring better in the warmer gulf, Kerr said. “A lot is going on in the ecosystem,” as species move into the niches once dominated by cod, a fierce hunter of smaller fish. The entire marine food web is shifting from top to bottom, she said, affecting everything from plankton to right whales. “I don’t think the traditional species will go away completely,” Kerr said, “but they will be here in very different numbers than they have been historically.”

Fewer Islands and a New Fishery

In the future, the coast of Maine may boast several fewer islands as sea levels continue to rise. “In my lifetime, sea level has come up about six and a half inches [16 centimeters],” Kelley said. The state is predicted to see between 33 and 55 centimeters of rise by 2050 and as much as 140 centimeters by 2100.

Monhegan Island, 16 kilometers off the mainland, boasts the highest sea cliffs of all the islands off the coast of Maine, rising 48 meters above the water. Credit: Mary Caperton Morton

“If you live on the coast of Maine on top of a rocky cliff, you’re going to watch the water slowly come up but it’s probably not going to do you much harm,” Kelley said. “But if you live on a low-lying glacial deposit, it will come at you much more rapidly.”

On human timescales of hundreds to thousands of years, the Gulf of Maine is predicted to keep warming, and marine species will need to adapt to their new warm-water world. “Going forward, [people] will need to adapt and start thinking about sustainable ways of harvesting new species,” Kerr said. “In 50–100 years, I think we can expect that it will be a whole new fishery.”

The longer-term implications of the persistent warming trend for both land and sea are ultimately unknown. “If Greenland’s ice sheet were to melt, it could stop the Gulf Stream, and that could kick-start an ice age literally within a few years,” Kelley said. “If we’re talking about million-year timescales, a lot can happen.”

—Mary Caperton Morton (@theblondecoyote), Science Writer

Citation: Morton, M. C. (2021), Windjamming on the warming Gulf of Maine, Eos, 102, https://doi.org/10.1029/2021EO210592. Published on 10 November 2021.
Text © 2021. The authors. CC BY-NC-ND 3.0
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