"That is what civilization is all about: farming replacing hunting."

The Next Seaweed Trail

by Peter Schiavelli

In the waning years of the last Ice Age, with mammoths still patrolling the tundra and much of the Northern Hemisphere still blanketed by sheets of ice a mile thick, humans first arrived in the Americas. What we know about this event is relatively little; archaeology is a field not celebrated for its certainty, and details of the past can be as murky as details of the future. We are pretty sure that the settlers came from Siberia, that their first American steps crunched down on the western tip of Alaska, and that this occurred sometime in a 25,000-year window, give or take a few millennia.

Beyond that, though, much of the story—how they got there, where they went next—remains unclear. It’s possible that they simply walked: with sea levels over a hundred meters lower than they are today, there was a swath of exposed terrain between Siberia and Alaska that would have been traversable. From there, picking their way through glacial gaps and cracks in the slowly-melting ice sheets, the migrants could have marched inland into Canada before plunging straight down into the heartland of the United States. Called the Ice-Free Corridor Hypothesis (or, alternately, the Clovis First Model), this has been the accepted theory for decades.


Recently, though, a competing hypothesis has been offered. Humans had been seafaring for tens of thousands of years, so instead of taking a very cold walk, the settlers could have taken a very cold boat ride. They could have sailed from Eurasia to Alaska, then followed the Pacific shoreline south. In and out of watercraft, disembarking where the ice was low, they could have skipped like stones along the coast, from Alaska to Canada to Oregon, and then possibly all the way down to Central and South America. In recent years, this theory, the Pacific Coast Migration Model, has been gaining steam, bolstered especially from an unlikely source: seaweed.

Macroalgae—seaweed—was one of Earth’s first multicellular organisms, appearing, in a very rudimentary form, around 1.5 billion years ago. Almost a billion years later, it helped catalyze the Cambrian Explosion. Today, there are three main types of macroalgae, known colloquially by their colors: green, red, and brown, with brown known more colloquially as kelp. Kelp is by far the largest algae—a single thallus of giant kelp can reach a length of more than two hundred feet. It grows by rooting itself to the ocean substrate and projecting up towards the sunlight in leafy, swaying columns—Jack’s underwater beanstalks. It prefers water relatively shallow and relatively chilly (cold water is more nutrient-rich), so it has a particular affinity for the North Pacific Coast. There, it blooms in dense forests, and its fronds lay thick on the water’s surface.


In keeping with its name, a kelp forest is rich in ecological biodiversity. Small invertebrates like crabs and urchins scuttle along the seafloor; eels coil in fissures; schools of rockfish and giant sea bass swirl around shaggy stipes while sea lions dart through the canopy and otters float on frond beds. The various algae provide protection from roaming predators and help mollify turbulent seaswell. Some forests house more than a thousand different species.

In 2007, University of Oregon archaeologist Jon M. Erlandson and colleagues published a paper in The Journal of Island and Coastal Archaeology titled “The Kelp Highway Hypothesis: Marine Ecology, the Coastal Migration Theory, and the Peopling of the Americas.” In it, he proposed that the first American settlers relied on kelp’s teeming ecosystems and calm waters to survive, and that the settlers’ route—often called the “Seaweed Trail”—was the result of following coastal kelp forestations like so many bread crumbs. If the Kelp Highway Hypothesis ends up being correct, it will provide a nice kind of symmetry, because the aspects of kelp that helped sustain our ancestors may yet do the same for us.

According to the United Nations Food and Agricultural Organization (FAO), the world is hurtling headlong towards a food crisis. In 2012, the FAO projected that, by the year 2050, the human population would approach ten billion people. To get a handle on what that number would mean, the FAO then analyzed how much more food the world would need to produce in order for its collective cupboards to not go bare. The amount was substantial. Seventy percent, it found. In order to feed a population of that size, global food production would need to increase by 70 percent. Although, in the years since, that exact number has been disputed to some degree, the main idea—that food production would need to increase drastically—is incontrovertible. The question is how.

Land would be the obvious solution. If global farmland expands, food production will as well, but its limits are as rigid as they are expensive. (“Buy land,” Mark Twain famously said. “They aren’t making it anymore.”) According to the FAO’s data, land allocated to arable production or permanent crops increased by 14.8% from 1961-2014. A significant amount, to be sure, but nowhere close to what would be required to feed a population of ten billion, and this rate is expected to dwindle: the FAO projects just a 4.8% increase from 2014-2050. (And there are scholars who argue we have already maximized our farmland potential. A paper published by the Rockefeller University in 2012 makes the case that it actually peaked in 2009.) Climate change is certainly not helping. A 2011 Stanford study in Science found, to no one’s surprise, that climate change is already crippling the yield and productivity numbers of the four main commodity crops (maize, rice, soybeans, and wheat), not to mention that our current climate trajectory has the well-documented potential to destroy some agricultural ecosystems altogether.

This is especially alarming given the ruthless deforestation (to say nothing of the human displacement) that would have to occur to create the open farmland to begin with. Essentially, to even try to meet the food quota through arable land expansion would be futile at best, catastrophic at worst.

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Water, on the other hand, presents an intriguing possibility. The quantifiable advantages to fish consumption are compelling. Compared with beef, finfish require fifteen times less feed and provide six times more protein for their body mass. Their emissions rate is three times lower, as is their rate of freshwater consumption, and they clearly don’t contribute to the erosion, desertification, and deforestation endemic to herds of grazing cattle. And bivalves—mussels, oysters, and the like—are practically perfect: not only do they not require additional food or water, but they are also emissions net-negative.

Oceans currently provide two percent of global food production while accounting for seventy percent of global surface area, so expansion would seem to be obvious. The problem is that all that space is not exactly teeming with fish just waiting to be hooked. In fact, the scientific consensus is that we are already overfishing at a wildly unsustainable rate, and that the global fish supply per capita has actually been declining for decades.

The response, just like on land, has been to build farms. Since 2001, aquaculture—the farming of aquatic plants and animals—has been the fastest growing food producer in the world, a phenomenon coined the “blue revolution.” Quantities of farmed fish have been outstripping those of farmed beef since 2013, and farming now accounts for more than half of all fish consumed. In 2016, Norway, which has a total population of less than six million people, harvested 1.18 million tons of salmon alone. The aquaculture market is currently valued at over $180 billion, and, with wild harvests unable to increase but demand for seafood expected to rise by as much as 35% over the next decade, the FAO predicts industry growth to accelerate from three to five percent every year. This would result in a market value north of $220 billion and total annual production above 100 million tons.

If this all sounds too easy, that’s because it is. The blue revolution, however promising, has been plagued by many of the same problems that have afflicted its more verdant sibling. Almost all current fish farms consist of some form of cage or pen—or lattice of pens—in water along the shore. In commercial aquaculture’s infancy, this was logical, because the simplicity of the structures and their vicinity to land was convenient and minimized costs. However, as demand has exploded, inshore farming infrastructure has struggled to keep up. Dense honeycombs of hastily-constructed farming nets lace slow rivers and stagnant lakes. The pens themselves quickly become overcrowded and dirty. In these conditions, disease spreads fast: a quarter of a million salmon died from a sea lice outbreak in fisheries in New Brunswick, Canada in 2017, with another quarter of a million then euthanized in order to keep the epidemic from spreading; Chile, meanwhile, lost almost three quarters of its harvest to an anemia disease in 2009. In response, farmers, particularly in poorer countries, suffuse the water with antibiotics and pesticides which then seep into food supplies and ecosystems. Static water has low circulation, so farming areas become thick with chemicals, fish waste, and unconsumed feed, choking seafloor critters and inducing unseasonable algal blooms. (These algal blooms—consisting of microalgae, not macroalgae like kelp—can be practically genocidal; in 2016, they killed 25 million salmon in Chile.) And the pens are not particularly reliable either. In 2017 more than 300,000 Atlantic salmon escaped from a farm in Washington, while almost 900,000 escaped in Chile last July. Marine Harvest ASA, a Norway-based aquaculture company that maintains farms worldwide, reported fifteen escape incidents in 2017 alone. The escaped fish are often foreign to their farming areas, so not only do their breakouts frustrate the farmers, but they can also jeopardize native marine populations and disrupt local ecological equilibria.


These issues are certainly not new, and as aquaculture has matured, farming countries seem to be putting more (or at least some) effort into addressing them. Norway, for example, has taken measures of varying levels of unorthodoxy: from instituting governmental regulations on the amount of salmon a farm is allowed to supply, to trying to raise its salmon in futuristic, underwater pods that would be indistinguishable from chicken eggs except that they have the diameter of a commercial helipad. Chile, for its part, saw a cohort of locally-operating aquaculture companies launch the Pincoy Project in 2016, a project which aimed to halve the country’s use of antibiotics in its salmon industry by the end of 2018. (The jury is still out on its success, but considering that reports have calculated the country’s previous antibiotic use to have been between two thousand and five thousand times that of other countries’, even if the Project succeeds, the industry would still have a long way to go.)

But while these measures are laudable, they have stunted farms’ supply growth, and with demand increasing and profits to be had, producers are getting impatient. The bottom line is that trying to increase fish harvests without sacrificing food safety or damaging ecosystems is exceedingly difficult, and that fish farms, as they have been generally conceived, seem to be rapidly approaching an upper limit on supply. But, with the food crisis impending, something has to be done. Perhaps the solution is to build a better farm.

It’s a clear morning in late fall, and the Captain Jack sits expectantly in the waters of Berth 58 at the Port of Los Angeles, near Long Beach. A vessel seventy-five feet long with a twenty-two-foot beam, it has spent most of its working life as a shark boat—a purpose indicated less-than-subtly by the painting that used to sprawl across its bow of a great white shark’s gaping, cuspidated mouth. (Though the shark, perhaps aware of its fate, arguably looked more aghast than it did aggressive.) Now, recently restored with a clean white bridge and enough varnish on its deck to coat the fleet of Lord Nelson, the Captain Jack is about five years into its second career as the main research vessel for Catalina Sea Ranch, an aquaculture company that farms mussels on the edge of the San Pedro Shelf. Reflecting the ship’s new priorities, its bow has been repainted: designs of cerulean, hillocky waves now roll along its sides, and the shark mouth has been replaced by a scallop shell of a size suitable for bearing Venus.

The Catalina Sea Ranch operates a hundred-acre plot about an hour and a half round-trip from the port. By the time we got there, the skies were dark and the waters restless. The farming area itself is a kind of coordinate system of plump, black, olive-shaped buoys systematically dotting the surface of the water like motion capture sensors. Heavy lines tether the buoys together, while the mussels collect on loops of rope draped along their lengths. The bivalves grow in thick, bristling clusters, and in the gray autumn light the obsidian shells gleam glossy and opaque. Twice a week, the lines are hauled in and harvested on the Ranch’s second vessel, the Enterprise—a boxy, low-slung converted riverboat that first took to water in World War II. All told, about 1500 pounds of mussels are collected per day.

What makes the Catalina Sea Ranch particularly notable is not what it farms, but where. Unlike the vast majority of fisheries, which operate close to shore, the Catalina Sea Ranch farms an area about six miles off the coast. It is one of the few domestic offshore aquaculture farms in the United States, and it is the only one permitted to operate in federal waters. It received its permit in 2012, after Phil Cruver, the Catalina Sea Ranch CEO, personally jumped through more than a million dollars’ worth of political, bureaucratic, and scientific hoops from a handful of agencies including the Army Corps of Engineers, the Environmental Protection Agency, the Food and Drug Administration, and the National Oceanic and Atmospheric Administration (NOAA).

Farming offshore minimizes many of the problems normally associated with aquaculture. The fisheries are large and uncramped since there is little competition for space. The constant flow of ocean currents flushes the area of waste and pumps in water clean and nutrient-filled, so the fish (or, in Catalina Sea Ranch’s case, mussels) are healthier and require less feed. Although there are oft-cited drawbacks to offshore farming—things like farm destruction and fish escapes, things generally related to the volatility of open water—they are far more solvable (or at least improvable) than what plagues nearshore farming. Creating a better fish pen is a lot easier than creating more shoreline, or cleaner water.

Locating the farm on the edge of the San Pedro Shelf was especially strategic. Mussels are called “filter-feeders” because they “eat” by catching microorganisms (phytoplankton, for example) free-floating in the water, which means that they can survive autonomously as long as water is flowing through their gills. Since the seafloor at the edge of the shelf drops almost instantaneously from a reasonable 150m to an abyssal 3000m, there is a continuous upwelling of deep, cold, phytoplankton-rich water onto the shelf. And expansion won’t be an issue; the Ranch is surrounded by 26,000 acres of U.S. Federal waters. Cruver is already finalizing plans to grow his operation tenfold.

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But possibly Cruver’s most prescient move was his choice of partnerships. It was clear to him early on that the success of the Catalina Sea Ranch would be inextricably tied to its sustainability. In stark contrast to the historically lax oversight of most global fisheries, the Catalina Sea Ranch is watched intently. NOAA representatives accompany the Enterprise for every mussel harvest, and they inspect every bivalve.

Operations are monitored real-time by a souped-up NOMAD buoy, donated by the NOAA and outfitted with a bevy of customizations and add-ons, that tracks everything from ocean salinity and current patterns to phytoplankton concentrations and predator locations. There were so many inspections that had to be passed and boxes that had to be checked getting the farm off the ground that it took Cruver five years to collect his first harvest. (And even that was too soon: the entire crop was lost because the mussels could not be federally inspected in time for distribution. The inspectors found nothing wrong.) And so, in 2017, with one eye on expansion and the other on sustainability, he partnered with Primary Ocean Producers, a nascent seaweed company run by two brothers, Scotty and Brian Schmidt, to surround his farm with kelp.


The earth’s oceans have, to this point, absorbed between thirty and forty percent of the anthropogenic carbon dioxide emitted into the atmosphere. Although this has obviously been very beneficial in mitigating the terrestrial effects of global warming, as human emissions have risen, the oceans are paying a price: according to the NOAA, besides the obvious warming, ocean waters today are thirty percent more acidic than in the pre-Industrial era. Acidified seawater, among its panoply of environmentally-devastating effects, is particularly corrosive to shellfish like mussels because it weakens—even dissolves—their shells and limits the amount of available carbonate in the water. (Carbonate is a key ingredient in shell-making). Kelp, however, fights this. It de-acidifies local seawater by photosynthesizing carbon dioxide three to four times more efficiently than terrestrial plants can. It is also fully self-sufficient, thriving on a combination of sunlight, carbon dioxide, and, conveniently, the cocktail of nitrates and ammonias that mussels expel as waste. The result is mussels that are stronger, healthier, and safer than can be found almost anywhere else.

Together, the Catalina Sea Ranch and Primary Ocean Producers represent the first steps of a much more ambitious plan for the San Pedro waters: the introduction of an integrated multi-trophic aquaculture (IMTA) farm, called the Oceans Operating System. The idea of IMTA is that it contains species of different trophic levels, so that one species feeds on the waste of another, like an arranged food chain, or ecological Rube Goldberg device. In the OceansOS model, for example, a pen of finfish is adjacent to a field of mussel lines, with macroalgae on both sides. Farmers feed the finfish, whose waste is then carried by the current first into the mussel lines, then into the macroalgae. The mussels extract the organic materials and the macroalgae extract the inorganic, along with the other mussel-produced nutrients. The environment is regulated and optimized both by the water flow and by the macroalgae, which keeps the area de-acidified for the bivalves and oxygen-rich for the finfish. The system is sustainable, productive, safe, and—particularly important with that FAO report still hanging over the industry’s heads—potentially expansive.

Jacques Yves Cousteau—environmentalist, aquanaut, and inventor of the first scuba set—saw this coming back in 1971. “We must plant the sea and herd its animals,” he said, “using the sea as farmers instead of hunters. That is what civilization is all about: farming replacing hunting.”

Last fall, Bill Gates posted a quiz on his website under the header “Can you beat my score on this climate change quiz?” It’s short, five questions, designed primarily to highlight some interesting—or at least lesser-known—facts about emissions. For example, avoiding one roundtrip transatlantic flight would apparently reduce a person’s greenhouse gas emissions this year more than switching to a hybrid car. (I missed that one.) The first question was particularly interesting: “if cattle were a country, where would they rank on emissions?” The answer is Jeffersonian: cattle would place third, just ahead of India and trailing only China and the United States.

Emissions associated with livestock exceeded seven billion tonnes last year. This was 14.5 percent of the world’s total and more than every sector save for electricity and industry. Livestock production occupies 70 percent of the planet’s agricultural land, 30 percent of all land total, and is a main driver of rampant deforestation, particularly in Latin America. The FAO itself is an outspoken proponent of livestock reform, releasing a report in 2006—“Livestock’s Long Shadow”—in which it claimed that the sector’s environmental impact is “so significant that it needs to be addressed with urgency.”

How does this relate to seaweed? Almost half of all livestock emissions are in the form of methane (much of it is literally burped out), and there is a growing body of evidence that indicates that adding seaweed to a cow’s diet is preposterously effective at mitigating digestive methane production. In one study out of Australia’s James Cook University in 2017, researchers who replaced just two percent of a cow’s diet with a type of red algae eliminated the cow’s methane production by 99 percent. Of course, kelp’s use as a feed should already have been obvious. It has a protein content equivalent to soy and nutrient content equivalent to kale; it is the fastest growing organism on earth (up to 30 inches per day in ideal environments) and requires no arable land or fresh water, so it can be harvested in large quantities while easing the strain on existing land resources. (It should also be noted that this is not exactly a novel idea: livestock have been fed some form of seaweed for millennia, from cows in Ancient Greece to sheep in Neolithic Scotland.)


And its uses extend beyond the comestible. Seaweed is found in cosmetics and pharmaceuticals; it is injected into agricultural fields as a soil treatment and synthesized as a biofuel. The seaweed market, recently valued by Grand View Research at a little over 10 billion dollars, has a five year projection north of 22 billion, with one forecaster (perhaps slightly optimistically) placing it above 87 billion.

But even without macroalgae’s usefulness as a product, without its value as a feed or a face cream or a fertilizer—even if all it did was sway in the ocean and clutch at the ankles of surfers—cultivating kelp fields would still be environmentally worthwhile. For years, macroalgae had been dismissed as a potential long-term carbon dioxide solution. (Scientists had found that macroalgae environments rarely contained a high volume of organic carbon, so they had largely concluded that macroalgae must be poor at storing it.) But in 2016, about a year before the James Cook study, an article appeared in Nature Geoscience titled “Substantial role of macroalgae in marine carbon sequestration.” The writers, professors Dorte Krause-Jensen and Carlos M. Duarte, had discovered that macroalgae’s effectiveness as a carbon sink had been vastly, vastly underestimated. According to their research, macroalgae was already sequestering about 634 million tonnes of carbon dioxide every year. For perspective, that number is roughly the equivalent of planting six million acres of trees and is enough to offset the emissions of the entire continent of Australia.

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To the truly monumental issues—world hunger, climate change—there are no simple solutions, no easy answers. The future, like the past, is murky, and the problems we face, like massive sheets of ice, are so vast and all-encompassing that often all we can do is make an educated guess. But as we look to the future, as we scan the horizon for where to go next, following the seaweed would seem to be a pretty good place to start.