By Alexandra Talty for Civil Eats.
Broadcast version by Suzanne Potter for California News Service reporting for the Solutions Journalism Network-Public News Service Collaboration

About 5 miles off the coast of Santa Barbara, California, a vast swath of giant kelp-Macrocystis pyriferia, which can grow nearly 3 feet per day-sways just below the surface of one of the world's first open-ocean seaweed farms.

Still in its research phase, the 86-acre project is operated by Ocean Rainforest, a company that aims to fight climate change by growing seaweed at scale: 1 million tons a year by 2030. Although an 86-acre terrestrial farm would be considered boutique, the Ocean Rainforest plot, floating in sight of the Channel Islands, represents a significant leap in size from the average U.S. seaweed farm of 1 to 4 acres-and a new frontier for ocean farming.

Supported by $6.2 million in Series A funding, for a total of $22 million from U.S. and European governments, grants, and venture capital, Ocean Rainforest also operates seaweed farms in the Faroe Islands and Iceland that supply the animal-feed, fertilizer, and cosmetic industries. The company's goal of substantially decarbonizing these industries-with seaweed, instead of petroleum feedstocks, as raw material-depends on the success of this farm. Growing seaweed in the open ocean, with room to exponentially expand, means the Ocean Rainforest team is tackling how to anchor crops in hundreds of feet of water, withstand intense weather, and monitor a farm that lies many miles from shore.

As Ocean Rainforest continues its research, the wider U.S. seaweed industry, still in its infancy, faces significant challenges. Several years of steady investment and scientific breakthroughs have helped it advance, but since 2023, funding has dropped precipitously, and so have retail prices for seaweed-based foods. In the meantime, a lack of government guidance by means of regulation and legislation makes it difficult for farms to gain traction. Seaweed is an extraordinary crop, offering multiple benefits to planetary and human health along with an array of business applications. But it's fair to say that right now, the industry is having growing pains.

The Investment Slowdown

In 2023, according to Phyconomy, a database that tracks the seaweed economy, seaweed funding in the U.S. abruptly began to sink, dwindling from a peak of about $100 million in 2022 to just $8 million for 2024 so far.

"We are in what I call the 'valley of disappointment,'" says Steven Hermans, who founded Phyconomy. American investors have become more sophisticated about startup investments, including in seaweed, he says. A few years ago, he adds, "They didn't know anything, and they were like, 'OK, we'll toss a couple of million into this.' Then, Everyone kept their money in their pockets during high inflation . . . [and] people realized . . . it will take a long time to build a market for American-grown kelp. Now they're asking better questions, and that will ultimately lead to better investments."

But for some companies, that won't matter. Since Civil Eats began this reporting project nearly a year ago, two of the largest and most well-known American kelp businesses have gone under: Running Tide, a carbon capture company, and AKUA, maker of kelp burgers.

Founded in 2017 by Marty Odlin, the Maine-based Running Tide was one of the most well-funded kelp companies in the U.S. before it shut down abruptly in June 2024. As its website stated, Running Tide aimed to build "humanity's operating system for the ocean," drawing down carbon via seaweed-inoculated wood chips. Seaweed naturally absorbs carbon as it grows, but unless it is harvested, it decomposes and releases carbon back. The chips, on the other hand, would sink to the deep ocean to decay, storing the carbon there for thousands of years, according to Odlin. Running Tide's revenue goal was to sell carbon removal credits to companies interested in decreasing their carbon footprint.

Running Tide garnered $54 million in Series B investments, including from Lowercarbon Capital, in 2022. In June of that year, an article in the MIT Technology Review questioned Running Tide's farming and business practices. Meanwhile, the company prepared to relocate to Iceland, having persuaded the Icelandic government to approve its wood-chip sinking.

In fall 2023, Running Tide sank 19,000 tons of wood chips into the ocean, selling the world's first marine Carbon Dioxide Removal (mCDR) credits to Microsoft and Shopify as part of a voluntary carbon market not regulated by government. In less than a year, the company shut down as criticism about its practices continued to swirl; Odlin cited a lack of American government support for the voluntary carbon market as the reason for the closure.

Although $54 million represented a fraction of the $380 million overall investment in the seaweed industry, some think the carbon-sink goal was too narrow, and overlooked all that seaweed could offer. "The long-term [carbon sink] potential attracted a swarm of speculators that took the industry in the wrong direction," says Bren Smith, founder of GreenWave, a forerunner in the ocean farming movement. GreenWave received roughly $6 million in 2021.

Smith believes that the dip in carbon-fueled funding will encourage the industry to embrace seaweed's many uses-as a good food for humans and animals, as a game-changing alternative to chemical- and carbon-intensive industries like fertilizers or plastics, and for its proven ecosystem benefits. Also, seaweed doesn't need arable terrestrial land, likely to diminish as wildfires and extreme weather events like drought increase. "I don't know if it's 100 years or five years, but we're gonna be growing huge amounts of food underwater," he predicts.

Lack of Federal Funding

The slump in private investment isn't the only financial challenge for seaweed. Scant federal funding adds to the struggle. In Europe, many ocean startups receive government support, according to Ronald Tardiff, Ocean Innovation Lead at the World Economic Forum, whereas in the U.S., most government funding goes to research institutions rather than for-profit companies. (The Department of Energy, an important source of research funding dating back decades, contributed some $20 million to seaweed research in the 1970s through its MARINER program, and continues to support science; see "Seaweed Investments by Category" below.)

"The E.U. has spent . . . . hundreds of millions of euros on R & D related to seaweed, in a way that the U.S. has not. And many startups have benefited from those E.U. projects," says Tardiff, pointing out that Ocean Rainforest, a for-profit entity, has received extensive E.U. funding. In China and Korea, where seaweed farming first developed into a larger industry, governments provide kelp seed to farmers for free or at a subsidized cost. The lack of state support in the U.S., says Tardiff, also means the American seaweed market is more tied to market fluctuations than its Asian and European competitors.

The paucity of both private and government funding makes it harder for seaweed companies to handle the high cost of farming and processing. "The ocean is uniquely expensive to operate on," says Tardiff, who also serves as the Lighthouse Lead of 1000 Ocean Startups, a global coalition of incubators, accelerators, competitions, matching platforms, and VCs that have pledged to back at least 1,000 "transformative" startups by 2030.

Basic seaweed farming equipment, like a boat, costs anywhere from $30,000 to $500,000; a single seaweed-line anchor-and a farm needs multiple-can cost $1,000. Also, because kelp is unusually perishable, it requires million-dollar investments in infrastructure equipment, like specialized dehydrators and freezers, to render it shelf-stable. Much of it is custom-built for this new food business.

Retail Slump Meets Inflation

Declining investment has hit kelp food companies particularly hard, since they're also dealing with shrinking grocery-store revenues, especially for consumer packaged goods (CPG)-which includes most seaweed foods. Also, high inflation rates mean a seaweed snack or seasoning won't do as well; when food prices are up overall, consumers are less likely to spend on foods that aren't familiar.

Describing the current CPG market as "brutal," Courtney Boyd, founder of AKUA kelp burger company, closed her operation this August. Boyd founded her kelp company in 2016, supported by GreenWave, and for a while it was thriving: She raised $4.5 million in funding from 2020 to 2024, according to Phyconomy. Looking back, Boyd regrets not having invested in farming, instead buying kelp wholesale from middlemen. She eventually began working directly with farmers in 2023, but it was too little, too late.

"With an inflationary environment, if you are a consumer-package company and you don't have a lot of oversight in terms of what's happening with the supply chain, you're in trouble when times are challenging," says Julia Paino of Desert Bloom Foods, a food investing firm.

Boyd's company will be taken over by the Maine Family Seafarm Coop, run by Ken Sparta, one of Boyd's partner farmers. The co-op plans to focus on direct-to-restaurant sales and piggyback off their existing oyster-selling infrastructure, avoiding the cost and complication of grocery-store sales entirely.

A Patchwork of Regulations

While investment in seaweed is lagging, so is America's regulatory framework. Each state has its own rules around seaweed farming. In Maine, for instance, farmers can only operate on leases after a period of public comment followed by approval, and only if the leases do not interfere with existing maritime operations. In Alaska, seaweed farmers can only cultivate seaweed varieties that grow natively within 50 kilometers of their farm. In California, no regulatory pathway even exists for seaweed farming in state waters. All commercial seaweed farms are on land.

Unlike terrestrial farming, no federal laws govern or guide ocean farming. Nor is there any federal tracking of seaweed landings, despite the edible seaweed business being worth nearly $2 billion in the U.S. This stands in stark contrast to terrestrial farming: At any given time, a citizen can look up exactly how much of a crop is grown, to the acre, on the U.S. Department of Agriculture (USDA) website, going back to the 1900s. This information is intimately tied to subsidies like the farm bill, which provides support to American farming industries like corn, soy, or pork. Without the clear picture that tracking provides, it's harder for money to flow.

In the case of seaweed, four federal agencies touch seaweed, but only lightly: the U.S. Army Corps of Engineers, whose regional offices are responsible for permitting every single seaweed farm in the U.S., but not for following up once those farms are established; the National Oceanographic and Atmospheric Administration (NOAA), which funds seaweed projects and education and tracks landings for fish and aquaculture, but not seaweed; USDA, which helps fund seaweed farms, on a limited basis, but doesn't regulate them; and the U.S. Food and Drug Administration (FDA), which regulates imported seaweed products and domestic seaweed-but only if it's part of a pharmaceutical product. The U.S. Coast Guard, responsible for mapping fisheries and other structures in the water, does not yet map seaweed farms.

With no single federal agency having oversight, and few guidelines on either the state or federal level, seaweed companies and farmers are left in limbo.

Sunken Seaweed, one of California's two commercial seaweed farms, has dealt with limbo for years now. Farmer Torre Polizzi raises dulse-a rich, meaty-tasting red seaweed favored by health-conscious consumers for its nutritional properties-in tanks on Humboldt Bay, in Northern California. California has no permitting process for seaweed farms in state waters, which extend anywhere from 3 to 12 nautical miles from land-an unsurmountable distance for most farmers. So, Polizzi is unable to grow his seaweed in the ocean, although dulse is native to the nutrient-rich, cold Pacific.

"That is where 99.9 percent of companies hit a wall in this industry in California," says Polizzi, the rush of pumped seawater humming in the tanks behind him. Each of his 10 tanks holds 1,200 gallons of constantly bubbling seawater, which tumbles the seaweed so it photosynthesizes more evenly.

Polizzi considers himself lucky to have found a home for his seaweed at all. He and his wife spent five years trying to find a location in California for their farm. They are able to pump saltwater from the ocean, crucial for a land-based seaweed company, through a relationship with Hog Island, the Northern California oyster restaurant and market, which already has a salt-water pumping permit for its oyster operation.

The California Coastal Commission, which oversees the permits, has not issued any new pumping permits in many years. In exchange for the seawater, Polizzi helps oversee a research bull kelp site for Hog Island, Greenwave, and The Nature Conservancy (permitted in the bay because it not commercial).

Even selling his fresh dulse and dried seaweed flakes at the local farmers' market was a battle: It took Polizzi six months of petitioning California's legislature to allow seaweed as a "cottage food," saleable at farmers' markets.

"We are here in California. We have some of the best marine science institutions in the world," says Polizzi. "We have the ability and tech to create the cleanest [seaweed farms] in the world. But we can't implement them."

Seaweed at Scale

Most of America's seaweed growers are small operations near the shore. Ocean Rainforest's "seaweed island" is miles from land and dwarfs them by several degrees of magnitude. It does share a similar growing technique with smaller farms, setting out buoys that support horizontal lines, inoculated with kelp, that then sprout fronds and grow under the sunlight. Instead of a few lines, though, there are hundreds here, arranged in immense grids under the ocean surface.

As a research farm, Ocean Rainforest is testing various seeding methods, grow depths, and length and spacing of lines to create a model that's efficient, economical, and replicable. They need to be able to monitor the site from shore and created an intricate buoy system so that they can see from the coast if anything disturbed their seaweed lines overnight or after bad weather. The company is also developing a harvesting machine that will reap the seaweed "using minimum cost and time."

If this project, set in a federal Exclusive Economic Zone (EEZ)-a strip of water that can stretch from 3 to 200 miles offshore-is successful, other farms could begin putting buoys in EEZs as well. The U.S. boasts the most EEZs in the world, a whopping 3.4 million square miles. That's a lot of ocean to potentially cultivate.

"There is no silver bullet when it comes to climate change, but seaweed can be part of that solution," says Eliza Harrison, until recently the director of California operations at Ocean Rainforest. Proponents of open-ocean farming say large-scale operations in EEZs could fulfill sustainability goals that smaller farms closer to shore can't: namely, substantial water bioremediation and enough raw material to supplant petroleum products in plastics and fuel. "Can you take this biomass that is naturally growing, can you cultivate it and then use it as a food and feed product, or use it as a way to improve people's well-being?" says Harrison.

While smallholder seaweed farms can boost maritime economies and provide job alternatives to commercial fishing, the lower quantities they yield makes it difficult to justify millions of investment in infrastructure. Additionally, seaweed from smaller farms wholesales at around $1 to $2 a pound, according to industry experts, a price that's not competitive in industries like plastics or textiles, where raw materials can start at $.70 (for PET polyethelene) or $.67 (for cotton) per pound. Large-scale farmed U.S. seaweed has yet to be marketed, but experts say that larger, automated-harvest farms could price their raw kelp more competitively, hitting below the $1 mark.

Replacing fossil fuel-derived plastics, a major contributor to global warming, with a climate-positive material like seaweed seems like a no-brainer. But some scientists have serious concerns about scaling up kelp farms. For one thing, huge kelp monocultures could threaten native kelp forests, responsible for drawing down a large portion of the world's carbon-around 56 million tons annually, according to a new study by Plymouth Marine Laboratory. That's equivalent to taking nearly 13 million cars off the road a year. Even more staggering, marine algae produces 50 percent of the world's oxygen.

That threat has already surfaced in China, which farms most of the world's kelp. In 2021, seaweed farming in the Northern Jiangsu Shoal, combined with warmer waters and human pollution, helped create green tides that sucked up oxygen and suffocated marine species for 81 days. Pests and bacteria infections are concerns, and so is the introduction of non-native seaweeds that could crowd out the native ones, or introduce new, disease-causing microorganisms. If the U.S. were to allow thousands of acres of farms in the EEZs, could that affect already suffering kelp forests in states like Maine and California?

These kinds of questions, and the fact that the industry is still new and evolving, say some experts, may explain why state and federal agencies and policymakers have been taking their time with guidelines. Rules laid down now could protect-or jeopardize-seaweed in U.S. waters. Those rules could also determine whether small seaweed farms will play an important and valued role in America's future, or begin to vanish, replaced by ever larger farms, repeating the history of farming on land.

The Beginnings of a Roadmap for Kelp

Slowly, some regulations are starting to take shape. A few states are beginning to safeguard against potential monoculture impact on wild kelp stocks. In Alaska, a "50-50 rule" protecting seaweed diversity requires every farm to collect its reproductive tissue for breeding kelp from at least 50 different plants, within 50 kilometers surrounding the farm. Maine mandates that farmers cultivate seaweed strains that are native to the state.

There's action at the federal level, too. A bill proposed in Congress in 2023, the Coastal Seaweed Farm Act, would direct the USDA and NOAA to establish an Indigenous seaweed farming fund to help Native Americans continue cultivating a food that has sustained them for thousands of years. The act would also create a joint study on how to responsibly scale seaweed in the U.S., and implement regulations based on those findings that would protect marine environments, measure the impacts and benefits of seaweed farming, and establish guidelines for monitoring farms.

Another bill, the Sustaining Healthy Ecosystems, Livelihoods, and Local Seafood Act-known as the SHELLS Act-proposes that the USDA create an office of aquaculture to promote funding, create regulations to guide the industry, and more. "The SHELLS Act is a crucial step toward enhancing U.S. food security and environmental sustainability through responsible aquaculture practices," said co-sponsor Congressman Nicholas LaLota (R-NY) in an email. His district is home to the state's first commercial seaweed farming operation and a thriving Indigenous seaweed farming co-op.

If passed, the SHELLS Act would create a federal body that could help seaweed farming evolve responsibly; the Advisory Committee, according to language in the bill, would "acknowledge the history, use, and preservation of Indigenous and traditional aquaculture practices and ecological knowledge." Mapping of seaweed farms-critical for maritime navigation and, potentially, wildlife corridors if large swaths of the country's EEZs are cultivated-could become a requirement.

The bill might incentivize a new round of investors, since seaweed harvest could be tracked just as simply as corn or soy. And it might give small farmers a boost. "Shellfish harvesters and seaweed farmers play an essential role in our food supply, but historically they haven't received the support they need to reach their full potential," said Congresswoman Suzanne Bonamici (D-OR), the bill's lead sponsor, in a press release. The SHELLS act, she said, "will help shellfish harvesters and seaweed farmers grow their small businesses while expanding blue carbon ecosystems that help address the climate crisis."

The past two years have been undeniably difficult for the seaweed industry, says Julia Paino of food investor Desert Bloom Foods. However, she sees promise in this ocean crop; it reminds her of how tofu came the U.S. in the 1980s. She would know-that's when her father brought the unknown food to American shores with his company Nasoya, convincing thousands of Americans to try a very healthy, unfamiliar food that was immensely popular in Asia, and ultimately to build the platforms and infrastructure that enabled its success.

"There's a lot of similarities . . . You have something that's been around for hundreds and hundreds of years, right? This is not a novel ingredient source that was just created in the lab. This isn't cultured meat. This is something that is steeped in significant cultural history, [with] a lot of tremendous health benefits, and now we know, also planetary benefits. It's a matter of helping educate consumers, right?" says Paino. "So, there's even more opportunity, I think, around what can be done with kelp. You'll continue to see excitement across a lot of investors-hopefully coming from a more informed place of, 'What is it? How is it grown? What's the type of infrastructure you need for it to thrive and be successful?'"


Alexandra Talty wrote this article for Civil Eats.


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By Sophie Kevany for Sentient.
Broadcast version by Suzanne Potter for California News Service reporting for the Sentient-Public News Service Collaboration

Fish, once a Friday penance for many, has recently become the "good meat" poster child. Fish farming has been touted as a way to help protect wild marine animals and, by some, even a way to feed the world. Yet a new study in Science Advances makes the case that farming fish comes at a much higher cost than previous estimates suggest, because of how much aquaculture relies on wild fish. According to the researchers, the total mass of wild fish required to produce farmed fish could be 536 percent higher than previous estimates. The drain on wild fish populations can in turn make it harder for vulnerable communities to find food. One of the core arguments for farmed fish - the idea that it protects wild fish by leaving them in the sea - ignores the fact that aquaculture relies on feed made from wild anchovies, sardines, herring, mackerel and other fish that many coastal nations rely on for sustenance.

The field of fish farming is no stranger to criticisms: overcrowded pens; poor fish health; inhumane killing methods; pollution; plastic waste from nets used to create pens, as well as diseases (spread by escaped farmed fish) that cause health problems for wild fish populations.

Nonetheless, the practice is growing. Farmed fish production is expected to have expanded by over 17 percent between 2022 and 2032, according to the United Nations Food and Agriculture Organization. By 2050, global demand for fish is expected to nearly double, thanks in part to an ever-increasing output of farmed seafood. Over a similar period, demand for fishmeal - the feed carnivorous farmed fish like salmon, trout and bass rely on - is projected to grow over seven percent by 2030.

"This is a hot topic in academic circles, but I don't think the public understands how fish farming works, especially in terms of its reliance on wild fish," Spencer Roberts, an environmental science and policy researcher at the University of Miami and a co-author of the new study, tells Sentient. In reality, says Roberts, aquaculture has simply shifted pressure from one set of fish to another.

The need for fish feed is creating problems for people too. "When we hear about fish farming feeding the world, it's not true. The reality is that it's starving people...in places like West Africa where 'reduction fisheries' are taking their fish," says Roberts, and selling or using them to turn into fishmeal. "Subsistence fishing communities are literally starving and being forced to emigrate," Roberts adds.

Part of how the aquaculture industry sold itself as the more sustainable option is thanks to what's known as the fish-in-fish-out ratio - the measurement of how many wild fish it takes to feed farmed ones. This figure, in essence, compares the number of how many wild fish are used as feed for fish farming, versus how many come out to feed humans. The calculation is used by the industry to demonstrate its efficiency, and therefore, its sustainability. It's used to make the case for how large a role it should play in a future with a growing global population, increasing planetary warming and shrinking natural resources, like farmland to grow food.

By focusing only on the ratio, Roberts and his co-authors argue, the true number of wild fish used to feed farm ones ends up obscured - indirect deaths are ignored, essentially - while outputs are maximized. This creates a misleading measurement.

There are a number of ways this plays out, but here's one example: so-called fish trimmings. Trimmings, which are the parts of the fish people don't traditionally eat (heads, tails and so on), are conventionally classified as by-products and subtracted on the basis that they are not wild fish. But according to a representative from The Marine Ingredients Organizations, only about 20 percent of trimmings for fishmeal come from farmed fish. The other 80 percent is from wild fish.

Once you adjust the calculation for the fish trimmings and other factors, the study finds, the volume of wild fish used to feed farmed fish could be over 300 percent higher than standard estimates. Taking other factors into account - when farmed fish that don't eat fishmeal are excluded, and indirect mortalities like slippage are included - it's even more dramatic. The total wild fish mass, according to the study, could be 536 percent higher.

It is not yet possible to convert the study's new percentage estimates into wild fish numbers, but Roberts says researchers working on the question believe reduction fisheries account for most fish taken from the ocean each year, killing over a trillion wild animals. These are animals who could otherwise be maintaining ocean health simply by staying in the sea, or helping to feed vulnerable populations.

Responses from fishmeal trade bodies to the new study varied, with the Marine Ingredients Organization favoring "a shared metric system" of lifecycle assessments, rather than fish-in-fish-out, and linking to a study that supports these as "the pathway to improved sustainability for all feed ingredients." A life cycle assessment quantifies the environmental impacts of a product, system or service from beginning to end.

The Federation of European Aquaculture Producers' general secretary Javier Ojeda was more upbeat about the study, saying its average ratio confirms that farming of fish reliant on fishmeal "is a net producer of aquatic food [which] should be heralded as great news," rather than a way to "demonize" it.

The Problem with Dewilding the Ocean

Fish farming creates another problem: dewilding. Separately, another new study finds mariculture - fish farming that takes place in the sea - is contributing to oceanic dewilding. Dewilding is a term for prioritizing human interests over ecosystems and, essentially, destroying the natural or wild world. Fish farms pollute the ocean too, with fish feces and uneaten food from farms creating excess nitrogen and phosphorus that can lead to algae blooms, depriving the water of oxygen.

The study looks at different dewilding categories, one of which is conceptual dewilding. Conceptual dewilding is a category that deals with human perceptions, which can set the stage for uncontrolled exploitation, says Becca Franks, co-author and assistant professor of environmental studies at New York University.

"The ocean is less explored than the moon... [but] as we map it for more places to put farms in and start to see it as a place to extract more resources from, the less we see it as a wild place, and the more we are going to be casual about destroying it," Franks tells Sentient.

Findings by Roberts and his team that aquaculture's dependence on wild fish is underestimated, are, Franks says, an example of "this rough, casual" approach to marine environments, and evidence that we are "not looking at the ocean as a wild space that should be approached with respect and caution."

Franks offers an example of humanity turning from a rough approach to a respectful one: whales. "We used to see them as floating oil reserves ...[but] with enough organizing and attention to who they actually were ... and allowing a bit of poetry to come in ... [we have] completely changed the way we think about whales, and it has allowed them to do better."

The bottom line, according to Franks, is that the critical role of oceans in storing carbon and mitigating climate change means we should take a very careful look at what kinds of aquaculture we want to proceed with, adding, "the details really matter."


Sophie Kevany wrote this article for Sentient.


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Scientists are sounding the alarm about growing dead zones in the Gulf of Mexico and beyond.

Dead zones are areas of water with hypoxia, or dangerously low levels of oxygen. Dead zones are caused by pollution, including fertilizer runoff from factory farms. The nutrients cause algal blooms which sink and decompose, and the process consumes oxygen on the ocean floor.

With this comes stratification, where differences in temperature among other factors prevent bottom waters from mixing with the oxygenated surface waters. Most species cannot survive long within a dead zone.

David Scheurer, oceanographer for the National Oceanic and Atmospheric Administration, said even short-term exposure can have effects.

"Hypoxia can have impacts on organisms, what we call sublethal impacts," Scheurer explained. "Instead of an outright fish kill, they can affect the development of fish and that can affect the ratio of males and females in the population, the fecundity of the species. That can eventually translate into larger population effects down the line."

This year's hypoxic zone in the Gulf was larger than forecast, at more than 6,700 square miles.

The Gulf dead zone is the largest in the country and the second-largest in the world. It forms every year and can vary in size. This year's dead zone far exceeds the 1,900 square-mile goal set by the Gulf of Mexico Hypoxia Task Force, a collaborative state and federal partnership.

Dead zones do not only threaten marine species such as shrimp and fish. They also upset local economies and imperil already fragile coastal communities living along the Gulf.

Scheurer pointed out climate change is likely to make the problem worse.

"Water holds less oxygen when it's warmer, organisms use more energy when it's warmer," Scheurer noted. "You also have the potential for enhanced stratification due to the temperature, as well as potentially increased nutrient inputs if climate change causes more rainfall in the watershed. "

The record 8,700-mile dead zone of 2017 reduced the brown shrimp habitat by 25%. In Louisiana and Texas, wild-caught shrimp landings are on a downward long-term trend, with historic lows in recent years.

Nutrient pollution goals set by the task force are voluntary and without enforceable state or federal limits, advocates stressed success will remain elusive.

This story is based on original reporting by Marlena Williams for Sentient.


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By Shi En Kim for Sentient.
Broadcast version by Suzanne Potter for California News Service reporting for the Sentient-Public News Service Collaboration

Deep below the surface of the ocean are the parts left mostly unexplored and where sunlight barely touches. One of these is called the mesopelagic layer, so-named for its spot in the middle of the pelagic zone. This "twilight zone" of the ocean contains more fish than at any other depth: estimates range from 1 to 10 billion metric tons. Until recently, the fish that dwell there remained mostly untouched by fishing vessels. But growing demand for farmed fish spurred the industry to explore new depths, urgently looking for more tiny fish to use as feed.

The "twilight zone" contains 90 percent of the ocean's total biomass in fish. These strange-looking creatures are well-adapted to the constant pall at 660 to 3,300 feet below. They often sport googly eyes, translucent bodies and bioluminescent veneers. Appearance and color aren't important considerations for citizens of a world shrouded in near-darkness.

What the dwellers lack in looks, they make up for in numbers. Since that remains a driving argument for fishing there, researchers have called for a moratorium to prevent future exploitation.

There Are Plenty of Mesopelagic Fish (For Now)

You can't order mesopelagic seafood in a restaurant or find it at the seafood counter. But there is plenty of seafood industry interest in mesopelagic fish - for turning them into fish oil supplements or aquafeed.

Aquaculture has long been touted as a way to relieve the burden on wild fish operations. Yet the industry itself needs wild fish to operate. Most aquaculture operations use small wild-caught fish, such as anchovies, as fishmeal for larger predatory fish that humans normally put on their plates. While the UN's Food and Agriculture Organization researchers say data on exact numbers is scarce, research suggests at least some fishmeal stocks are teetering towards depletion. In West Africa, for example, feedfish have been over-harvested by foreign companies. And illegal operators are devastating marine biodiversity, and threatening local livelihoods.

As a substitute for wild-caught feed, some aquaculture operators raise their fish on a vegetarian diet such as soy. But many experts are quick to point out the inanity of this alternative: it's like forcing a lion into an herbivore lifestyle, Xabier Irigoien, a researcher at AZTI and King Abdullah University of Science and Technology tells Sentient. "We are actually using land and freshwater to grow soy - to grow a fish that really doesn't need freshwater or land. So we are doing really odd things in terms of food."

At the same time, our global appetite for fish, especially farmed fish, continues to rise, and the industry is exploring new options. In late 2023, the Norwegian firm Nofima conducted a three-month trial of feeding farmed salmon mesopelagic catch. The researchers observed their salmon growing faster than their counterparts fed a typical protein diet. "It's very promising," Ingunn Marie Holmen, a research manager in fisheries technology at the Norwegian research institute SINTEF Ocean, tells Sentient. Nofima "had to actually stop the trial one week early because they ran out of feed."

Not everyone is on board, however. Since 2020, researchers have called for a global moratorium on mesopelagic fishing, concerned that plumbing these new depths for fish could take a toll on climate action and biodiversity.

Fish Capture and Store Carbon in the Sea

All fish, including mesopelagic fish, play a vital role in sequestering atmospheric carbon, slowing the pace of climate change by taking emissions out of the atmosphere. Deep-dwelling mesopelagic fish are even more vital to that process, simply because of where they live. Many of these fish undertake a daily vertical migration, surfacing at night to feed, then returning during the day to hide from predators. Mesopelagic fish exhale carbon dioxide, poop and themselves get eaten by other mesopelagic hunters. And all of these activities help ferry carbon from surface waters to the deeper ocean, where it can be stored more effectively than on land.

Another ecological downside of mesopelagic fishing is the damage to ocean biodiversity. The role of mesopelagic fish in the marine food web is still largely unknown. But researchers know that several epipelagic species, such as dolphins, swordfish and tuna, feed on their submarine neighbors. Trawling in the mesopelagic zone might risk disrupting fisheries at the ocean surface, including those the industry thinks of as the most valuable at market.

"We don't know the system well enough to start harvesting mesopelagic fish," says Middle East Technical University oceanographer, Deniz Dişa. Last June, Dişa and her team published a study modeling the impact of mesopelagic fishing in the mid-Atlantic Ocean. The researchers found that even removing a conservative fraction of the mesopelagic stock would lead to cascading effects of carbon cycle disruption, with a decrease of 14 percent in total carbon movement, and food web chaos. According to the team, fishing in mesopelagic waters would only have a 20 percent chance of being sustainable.

The bottom line, Dişa says: the consequences are "not that simple." And a growing number of ocean researchers agree, arguing that fishing deeper isn't a solution to dwindling marine stocks - it only punts the problem from one corner of the world to another. Given their unique ecological roles in biodiversity and carbon sequestration, mesopelagic fish are just as worthy of protection as those near the surface, if not more.

"This is a group which is unlike most of the species that we exploit at the moment," says Callum Roberts, a University of Exeter marine biologist who is among those calling for a mesopelagic fishing ban. "If there's any part of the ocean that you really don't want to mess with, it's the mesopelagic fish."

Technological Hurdles Add Another Layer of Caution

For now, there are a number of challenges keeping mesopelagic fishing at bay. Experts say this type of fishing requires high fuel consumption, for one. The fish are also very small, some no larger than a finger pad, so fishers need to deploy nets with fine mesh and contend with high levels of drag.

Mesopelagic fish also spoil easily because they're full of digestive enzymes, so they have to be processed or frozen promptly. "You almost can't touch it before it's all porridge," Holmen says. According to marine scientist Stein Kaartvedt, one South African ship's mesopelagic bycatch apparently caught fire because it was so oily.

The fish that hang out in the twilight zone can also be tough to catch. Most are stragglers - they don't congregate while swimming to make for an easy one-scoop kind of bounty - and they are also notorious for dodging nets.

"They are everywhere," says Kaarvedt of the University of Oslo, but that doesn't mean they are easy to catch. "The main thing with fishing is not whether we have 1 billion or 10 billion, but whether you have sufficient concentrations to make fishing feasible."

Mesopelagic Fish Ended Up a Red Herring

The Norwegian fishing industry seems to have come to the same conclusion. In the late 2010s, a group of companies conducted a trial of mesopelagic fishing. The vessels brought in abundant catch in their first attempt, but the next two tries yielded near-empty nets. Since then, the fishing industry there has moved on to more lucrative targets, such as cod and herring. Mesopelagic fishing interest has also watered out in Iceland and South Africa, in favor of mackerel and sardines.

Across the world, more of the fish we eat comes from farms rather than wild-caught fisheries these days. But the proportion of fish stocks that have been classified as overfished has also been growing in tandem. Today, that fraction is 30 percent; and fish populations that are at capacity come in at 60 percent.

Although practically unnecessary at the moment, a moratorium on mesopelagic fisheries would help thwart future exploitation, says University of Exeter's Roberts. Nevertheless, all that research on the mesopelagic zone is far from wasted, industry proponents say. This is a rare instance of a marine industry sinking time and money into conducting a full cost-benefit analysis before diving in head first. "It could be an example of how to approach expansion of any kind," says another researcher, Irigoien, for fish as well as other ecosystems and natural resources.


Shi En Kim wrote this article for Sentient.


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