By Seth Millstein for Sentient.
Broadcast version by Suzanne Potter for California News Service reporting for the Sentient-Public News Service Collaboration
The global population is projected to hit at least 8.5 billion people by the end of the decade. As more of us become aware of the disastrous environmental impacts of livestock production, some climate-conscious consumers are turning to seafood as an alternative to meat. But the seafood industry has its own problems, as the rise of overfishing - and its harms - has made clear.
"Overfishing is a serious global problem, threatening ocean wildlife and biodiversity, as well as seafood supplies," Dr. Beth Polidoro, Director of Research at the Marine Stewardship Council, told Sentient in a statement. "And unfortunately, it's a problem that's increasing, and has been for several decades."
Seafood consumption has risen dramatically since the mid-20th century: Between 1961 and 2021, the average person went from eating around 20 pounds of seafood every year to around 44 pounds, according to Our World in Data. Since then, commercial fishing has become a $229 billion industry, and according to a 2019 study, between 1.1 and 2.2 trillion fish are caught every year.
But as our appetite for seafood has increased, so has the frequency of overfishing. Between 1974 and 2017, the share of the world's oceans that were overfished jumped from 10 percent to a little over 34 percent, according to the Food and Agriculture Organization of the United Nations. Marine ecosystems around the world have suffered as a result.
But what exactly is overfishing, why is it such a big problem - and what can be done about it? Let's dive in.
What Is Overfishing?
Broadly speaking, overfishing is when fish in a particular region are caught at a faster rate than they can repopulate. In theory, this could ultimately lead to the extinction of the species, although in practice, it isn't clear that any fish species is confirmed to have gone extinct solely due to overfishing - although this might soon change, as we'll see.
Overfishing is directly related to the concept of yields. For any fish population, there's an "ideal" amount of fishing that maximizes the number of fish that can be caught in the long-term. Overfishing is simply when the fish in a region are caught at a faster rate than this amount.
"If you don't fish at all, you obviously don't get any long-term catch," Ray Hilborn, professor at the University of Washington's School of Aquatic and Fishery Sciences, tells Sentient. "If you fish too hard, you get very little long-term catch. And in the middle is this theoretical sweet spot that produces what's called 'maximum sustainable yield.'"
Hilborn says that in general, the maximum sustainable yield of a given fish population is "roughly equal to the fraction of fish who would die from natural mortality." For example, if 20 percent of the fish in a certain population would die from natural causes over the course of the year, this implies that fishers shouldn't catch more than 20 percent of that fish over that same period of time.
In contrast, you can look at the overfishing that occurred on Canada's northeast coast throughout the 20th century. Canadian cod was harvested so over-aggressively that by 1992, the region's cod population had fallen to less than one percent of its historic norm.
To ensure the species wasn't wiped out completely, the Canadian government announced a moratorium on cod fishing in the region, a decision that resulted in 30,000 people losing their jobs. And yet, the cod population in the area still hasn't recovered.
Overfishing is often grouped under the larger umbrella of illegal, unreported and unregulated fishing, (or IUU), by scientists, academics and policymakers.
What Are the Consequences of Overfishing?
Overfishing has a number of deleterious environmental impacts. Some of them, like bycatch, are inherent problems with fishing in general that are exacerbated by overfishing practices; others, like trophic cascades, are specifically caused by overfishing.
Ecosystem Destruction Due to Overfishing
Ecosystems involve a complex web of interactions between different species, and in a healthy ecosystem, these interactions naturally balance themselves out in a sustainable way. If predators become too populous, there won't be enough prey to feed them, so some of the predators will die off, which then gives the prey species time to repopulate. This repopulation gives the predators more access to food, thus allowing their species to repopulate, and so the cycle repeats itself.
Overfishing disrupts this natural process, and the consequences can be varied and far-reaching.
Take, for instance, the relationship between parrotfish, coral reefs and algae. Algae thrives in coral, but when it's allowed to grow unchecked, it can damage and kill the coral species. Luckily, parrotfish dine on algae, and so by simply going about their lives, they play an accidental but very important role in maintaining the health of coral reefs.
But when parrotfish are overfished and their population dwindles, this check on algae growth is removed, and the coral reefs suffer. This isn't just hypothetical: A study published in 2015 found that overfishing of parrotfish and other "grazers" has been a primary driver of the steep decline in the health of Caribbean coral reefs over the last 50 years.
This type of phenomenon, in which a change in a predator's population has a downstream effect not only on its own prey but on other species as well, is what's known as a trophic cascade. And overfishing has caused a number of trophic cascades.
The overfishing of sharks on the Atlantic coast led to a collapse in scallop populations, for instance, because sharks eat clownrays and clownrays eat scallops. Overfishing of cod and other sea urchin predators has helped degrade kelp forests, which is an especially big problem given the many environmental benefits that kelp provides.
One of those benefits is the absorption of carbon dioxide from the atmosphere, which brings us to another dire consequence of overfishing: rising global temperatures.
Overfishing Causing Climate Change
The idea that overfishing can exacerbate climate change might sound counterintuitive; after all, what do the number of fish in the sea have to do with the temperature outside? As it turns out, quite a bit.
The ocean absorbs a massive amount of carbon dioxide from the atmosphere: around three billion metric tons every year, or one-third of all global emissions. What's more, the ocean absorbs more carbon than it releases, which makes it a carbon sink - the world's biggest, in fact. Because carbon dioxide is one of the primary greenhouse gasses, the ocean plays an enormous and crucial role in slowing the rise of global temperatures.
But overfishing has diminished the ocean's ability to absorb carbon. That's because ultimately, it's the creatures in the ocean who are sucking up all of this carbon.
The process begins when phytoplankton at the ocean's surface absorb carbon dioxide from the air. These microscopic creatures are then eaten by zooplankton and other larger species, who absorb the phytoplankton's carbon, and so it goes throughout the ocean's food web - all the way up to whales, who can store up to 33 tons of carbon dioxide over the course of their lives.
This is an effective form of carbon storage, because the carbon remains in the ocean and out of Earth's atmosphere even after the fish die - unless, of course, the fish are caught by humans and removed from the ocean, in which case all of that carbon is released back into the air. Overfishing greatly exacerbates this phenomenon: According to a Sentient analysis, overfishing results in an additional 5.6 million metric tons of CO2 being released into the atmosphere every year.
Bycatch Due to Overfishing
Bycatch is what happens when fishers accidentally catch, injure or kill species that they weren't intending to catch. Common victims of bycatch include dolphins, sea turtles and over 200 other species that are protected, endangered or threatened.
The sheer extent of bycatch can't be overstated: It's been estimated that over 40 percent of all fish caught annually are actually bycatch. What's more, bycatch results in the death of more than 650,000 marine mammals - that is, aquatic creatures other than fish - every year.
Hurting Local Fishing Communities
Many coastal communities around the world rely on a healthy supply of local fish to feed themselves. Overfishing and other forms of illegal, unreported and unregulated fishing have hurt these communities in a number of ways, and it's often developing countries that suffer.
In Sierra Leone, for example, overfishing in coastal waters has forced local fishers to travel further and further into the sea to catch fish, exposing them to increasingly dangerous weather conditions. In 2022, Sierra Leonean fishers told the Guardian that they're struggling to feed their families thanks to the dearth of fish caused by overfishing.
Much of the time, the overfishing causing this is carried out by foreign nations. In Japan and South Korea, for instance, more fish is caught by other countries' vessels than by domestic fleets. In Sierra Leone, most of the large trawlers used to harvest fish are owned by European and Asian companies, according to the United Nations, and 40 percent of industrial fishing licenses in the country are owned by Chinese vessels.
Possible Extinction Due to Overfishing
As mentioned earlier, no fish species is confirmed to have gone extinct solely because it was subject to overfishing. But that may not always be the case: A 2021 study by the World Wildlife Foundation concluded that one-third of all shark, ray and chimaera species are currently at risk of going extinct thanks to overfishing.
How Can We Stop Overfishing?
End Harmful Fishing Subsidies
Governments around the world spend a lot of money subsidizing their respective countries' fishing industries. Though some of these subsidies are benign, others have been blamed for incentivizing overfishing and contributing to all of the above problems. For instance, many governments subsidize or discount the fuel for shipping vessels, allowing them to fish longer, harder and farther away.
The world's governments spend over $20 billion on what researchers call "harmful fishing subsidies" every year, according to a 2019 study in the journal Marine Policy. Eliminating, or even substantially reducing, these subsidies would go a long way to curb overfishing, according to a range of experts and marine advocates.
Protect More of the Ocean
Marine Protected Areas (MPAs) are areas of the ocean in which legal protections have been established for conservationist purposes. The nature and degree of these protections vary, but many of them have been effective at reducing or eliminating overfishing within their boundaries.
However, MPAs only cover a miniscule portion of the ocean. According to the UN, less than nine percent of the ocean is protected by MPAs - and that's one of the higher estimates. The Marine Conservation Institute puts the number at around five percent, while a 2024 report by a group of NGOs claimed that, due to lax enforcement and weak protections in some MPAs, only 2.8 percent of the ocean is effectively protected from overfishing.
Regardless of which estimate is most accurate, the upshot is clear: Over 90 percent of the ocean is unprotected. Bolstering MPA enforcement and bringing more of the sea under legal protections - which the UN, to its credit, is currently attempting to do - would be another powerful check against overfishing.
Eat Less Seafood
One factor driving overfishing is that consumers are increasingly developing a voracious appetite for seafood. Some coastal communities are dependent on fish for their diet, but the rest of us can be mindful of overconsumption, and how it impacts wildlife, including fish and other marine life. One alternative: the many sources of plant-based protein that don't exact anywhere near the environmental cost of seafood (or meat, for that matter).
The Bottom Line
Although it has become increasingly popular to think of fish as a sustainable alternative to meat, the far-reaching environmental, animal and human impacts of persistent overfishing throws a wrench into that narrative. If industrial fishing operations continue at their current pace, so will overfishing - at high cost to marine habitats and our ability to stave off the worst effects of global warming.
Seth Millstein wrote this article for Sentient.
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By Leilani Marie Labong for FoodPrint.
Broadcast version by Suzanne Potter for California News Service reporting for the FoodPrint-Public News Service Collaboration.
At a recent pop-up in Healdsburg, California, to preview Chef Jacob Harth's forthcoming sustainable West Coast seafood restaurant, Winnie's, I tasted my first raw, line-caught Pacific sardines. (The tinned version stars in one of my first food memories, so this new experience was long overdue.) Cured in seaweed salt and gently warmed over coals, the dense and oily fish had been reeled in less than 24 hours before from the ocean off San Diego. But since commercial fishing of Pacific sardines was closed in 2015 (the third moratorium implemented since 1967 to rebuild the boom-and-bust population), how in the world did these forage fish end up on my fork?
Turns out, they were caught up in a targeted mackerel harvest and sold as bycatch, defined as "anything that is caught in the fishing process beyond the species and sizes of the targeted marine organisms," according to the Food and Agriculture Organization (FAO) of the United Nations. This definition casts a wide net and includes, for example, ocean sunfish (Mola mola), an unmarketable bycatch of the California swordfish fishery; the 10 orcas accidentally ensnared off Alaska's Aleutian Islands last year by bottom trawlers in pursuit of yellowfin sole and Pacific Ocean perch; and the Pacific sardines at Winnie's, an incidental catch of an otherwise protected, non-target but quite marketable species.
"Anytime you put a hook in the water, you can't be sure what's going to bite," says Dave Rudie, founder of the seafood market Catalina Offshore Products in San Diego. "So inevitably you're going to get some bycatch." Thanks to the active commercial ban on the fishery, the National Oceanic and Atmospheric Association (NOAA) currently considers the Pacific sardine stock "not overfished." So, onto my plate they went.
What is bycatch - and when is it edible?
"There are multiple meanings of bycatch depending on who you talk to," admits Elizabeth Hellmers, a senior environmental specialist with the California Department of Fish and Wildlife (CDFW). "But as long as their populations are healthy and being managed properly, it's beneficial for the entire production pathway [from fishers to consumers] to use as much bycatch as possible."
Domestic bycatch is monitored by the National Marine Fisheries Services and the U.S. Fish and Wildlife Service, with help from heavy-duty legislation like the Marine Mammal Protection Act, the Endangered Species Act, and a host of other legal provisions that aim to keep our sea stocks flourishing. Even though a 2018 assessment by the FAO estimates that bycatch amounts to nearly 10 percent of the global catch, an NOAA review of standardized bycatch reporting acknowledges that some information about bycatch is predictably anecdotal. "It's hard to count fish in or out of the sea," quips Harth.
Eclipsed by more newsworthy bycatch tragedies, the sustainable utilization of bycatch often goes unsung. Adrian Hoffman, cofounder of Bay Area-based Four Star Seafood (a "first receiver" that "lands" fish and shellfish directly from fishermen before distributing it to restaurants and markets), assumes that the average consumer doesn't think about bycatch much. Why would they need to when halibut, salmon and cod - the pelagic mainstays of American gastronomy - are always in ready supply at the grocery store?
"If consumers do think about bycatch," Hoffman says, "their impression of it is probably something like, 'Oh, some people went fishing and caught all this stuff they can't use, so they just threw it back over.'" Evidently, the average consumer of Hoffman's imagination is not far off the mark: conservation nonprofit Oceana reports that approximately 17 to 22 percent of annual U.S. bycatch is "discarded at sea, likely already dead or dying," while in Europe that number is closer to 50 percent, much to the detriment of marine environment.
Since the U.S. imports 62 to 65 percent of its seafood, utilizing bycatch seems like a legitimate strategy - along with, for instance, sustainable stateside aquaculture - to alleviate that burden. Rudie warns of the "transfer effect," or the shift in supply from well-managed U.S. fisheries to foreign fisheries with potentially questionable standards. "It's quite a trade-off," he says forebodingly.
In grassroots fashion, seafood purveyors and chefs are endeavoring to create awareness around utilizing bycatch, which is doubly sustainable if harvested through methods like hooks, harpoons, bottom-set longlines and traps. Slower and more targeted, these methods produce a micro-catch compared to the weighted bottom-trawler nets typically used in industrial fishing operations (which are very restricted, at least on the West Coast). Giant trawlers not only account for 78 percent of global discards, but they also send plumes of carbon dioxide into the atmosphere and contribute significantly to ocean acidification as they sweep the seabed indiscriminately.
Sustainably caught West Coast bycatch can include Pacific octopus and wolf eel from Dungeness crab pots and skate or dogfish from bottom-set longline black cod. "At some point we're going to need to be very familiar with bycatch," says Harth, "because that's all that's going to be left to eat if we keep going after the same old fish."
Advocating for bycatch
With Winnie's opening in summer 2025, and numerous pop-up previews until then, Harth continues his crusade to advance the use of bycatch and other undervalued sea species, a passion that originated while sportfishing with his father near their family home south of Tillamook Bay, Oregon, and commercial fishing for his erstwhile Portland seafood restaurant, Erizo.
Over the course of his lifelong seafaring history, Harth has developed certain insights about bycatch or even underutilized species. For instance, red and brown rock crab, which can be found in great abundance along the West Coast, make a more robust seafood stock compared to the highly sought-after Dungeness, which has a more delicate flavor despite being "stressed out." While lingcod and rockfish are common targets for rod-and-reel fishers casting off jetties in Oregon, the chef also enjoys the mild and flaky flesh of lesser-known cabezon or monkeyface eel that occasionally hook on the same lines. And at hyper-regional Erizo, he eschewed the wild mussels and ocean-farmed oysters from eastern Canada's Prince Edward Island - a frequent fossil fuel-guzzling flex on West Coast restaurant menus - for Oregon's own gooseneck barnacles, littleneck clams and surftide mussels, which more meaningfully evoked sense of place.
"If anyone could influence someone's opinion about bycatch species, it might be a chef or a restaurant," says Harth. Indeed, he is the latest in a legacy of toques who have fought food waste with kitchen initiatives; consider Dan Barber's WastEd series, which turned food scraps into delicious dishes like fried skate-wing cartilage and beet-pulp burgers, and Massimo Bottura's Food for Soul program, which feeds the homeless warm and nutritious meals made from high-quality restaurant discards. As Katherine Miller, author of "At the Table: The Chef's Guide to Advocacy," said in an interview with The Bittman Project, "Chefs are well suited to help accelerate advocacy work. They can help translate complicated topics into something easier to understand. [They] have too much influence on our food choices ... to just sit on the side lines."
Harth's advocacy brings attention to a waterfall of lost resources and opportunities - the hallmarks of a broken food system - associated with blindly jettisoned legal bycatch, which include but aren't limited to a recreational fisherman's missed meal, the massive carbon demand of importing seafood from foreign countries, and the overfishing of popular species. His activism also manifests in a respectful, elevated approach to preparing these so-called discards: In his purview, house-made butter is flavored with smoked Kellet's whelks, a bycatch of Santa Barbara's lobster fishery. Of the Pacific octopus often found in crab pots, he makes wood-grilled skewers slicked in wild mushroom oil. (Doing their part for the survival of the species, Pacific octopus spawn hundreds of thousands of eggs and die soon after, often at the claws of crabs, which is why they're regularly found in the pots.) And turning purple sea urchin into uni-on-toast is especially beneficial, since the urchin is an invasive species with a voracious appetite for the valuable kelp forests along the Mendocino Coast.
But if mild white fish is the extent of your seafood palate (no judgment here), Harth assures that wolf eel and the small shark species dogfish - whose low marketability in the U.S. may be due to their canine-related monikers among other stigmas - will readily appeal. What's considered bycatch in America may be target catch elsewhere in the world, theoretical proof of concept for their culinary applications. In Ensenada, Mexico, dogfish and angel shark are the preferred proteins for Baja-style fish tacos - a nod to the 1950s and '60s Japanese fishermen who introduced their traditional tempura-battered shark to the region. "That's part of the appeal of most bycatch," says Harth. "It's different, but also familiar."
Marketing for sustainability
Also fighting current on the way to marketability is opah, the world's only fully warm-blooded fish species, a biological advantage that helps them swim, digest and react faster than their cold-blooded cohorts in cold, deep ocean. Its flesh may have a beautiful pinkish-orange hue reminiscent of tuna, but some of its cuts, particularly the adductor muscle, taste entirely, well, beefy. And flavor hasn't been the only barrier to more widespread inclusion on the American dinner table: Its appearance is also unusual. Opah looks almost celestial, with gold-rimmed eyes and a full moon-shaped body that's speckled, silvery and rosy around the edges. For some, the fish may look too otherworldly to eat.
In 2013, Dave Rudie of Catalina Offshore Products received a call from fishermen who were harvesting Pacific bluefin tuna between Hawaii and California. They had found the target species in high numbers, though a significant fraction of the catch comprised opah. Still, Rudie agreed to purchase their 30,000-pound harvest, and subsequent monthly deliveries thereafter, to reboot the tuna supply in San Diego specifically for the sushi market. The city's once-booming tuna canneries ceased operations in the 1970s and '80s, parallel to the decline of Pacific bluefin and yellowfin species in the area due to overfishing.
"But opah was not a popular fish," Rudie says, "so we had to figure out how to sell it." He applied for, and received, NOAA's Saltonstall-Kennedy Grant, which funds efforts to "help fishing communities optimize economic benefits by building and maintaining sustainable fisheries." Catalina Offshore began working with the Southwest Fisheries Sciences Center to find ways to promote the fish using social media, retail sales and local chefs' innovative recipes, such as opah burgers and opah pastrami.
Their marketing savvy paid off. But just as demand for the fish began to rise, the amount of opah bycatch began to trough. "Good old supply and demand," muses Rudie, who sold Catalina Offshore about a year ago and has since pivoted to promoting yet another misunderstood species, the aforementioned purple sea urchin. "That's the free-world capitalist system for you."
Bycatch for the future
The latest Fisheries Economics of the United States Report, from 2022, revealed that the U.S. commercial and recreational saltwater fishing industry generated $321 billion in sales and supported 2.3 million jobs. Climate activist Ian Angus traces the origins of capitalism back 5,000 years to when "fishing for sale rather than consumption developed with the emergence of class-divided urban societies." Additionally, he cites the first mention of overfishing in texts dating back nearly 2,000 years, when the Roman poet Juvenal lamented having to import fish from Corsica and Sicily because "our waters are already / Quite fished-out, totally exhausted by raging gluttony." Sounds like overfishing, or the depletion of fish stocks due to a faster rate of harvest compared to the natural tempo of renewal, is a tale as old as time.
Can utilizing bycatch tackle such an ancestral problem? Maybe not entirely, but Hellmers of the CDFW thinks that using less-popular species can at least take "a little bit of pressure" off the main ones. "We have a huge demand for seafood in this country, so anything that can be used and sold is beneficial for the fishers, the consumer, and from a management perspective," she says.
If the importance of utilizing bycatch isn't obvious by now, consider the fact that such familiar fins of American eating - like petrale sole, ocean perch and Chinook salmon - are among the 30 species presently considered threatened and endangered from overfishing, dams and pollution in the California Current, an oceanic current and dynamic ecosystem that flows from southern British Columbia, Canada, to southern Baja California, Mexico. In 2018, the fall-run Chinook that historically spawn in the Klamath and Sacramento Rivers were determined overfished; in 2023, the fisheries were "declared a disaster" by California's secretary of commerce. Even though Chinook and other salmon runs like coho have been in decline for decades, California has only canceled the last two salmon seasons. Currently considered non-legal bycatch in the Golden State, captured salmon must be released back to the waters from whence they came.
But perhaps the proverbial tides are turning. Earlier this year, dams along the Klamath, a major California-Oregon watershed, were removed and salmon have since been spotted in reaches of the river formerly unreachable for more than a century. Despite the potential to appeal to a wider audience once salmon fishing comes back online, Harth plans to stay the bycatch course. "There will need to be many, many more improved seasons for me to even consider putting salmon on my menu," says Harth. And likely no shortage of bycatch to fill the void.
Leilani Marie Labong wrote this article for FoodPrint.
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