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Consider the Mort

Examining the Literal and Figurative Underbellies of the Fish-pain Debate
DISCUSSED
Five Black Chutes, Humanity’s Earliest Triumphs of Husbandry, Rotary Club Signage, A Strip-Mall Starbucks, A Decerebrate Cat, Sham Rage, The November 1874 Edition of Scientific American, The Human Urge for Narrative, Your Favorite Stuffed Animal, Scientists Rolling Their Eyes, Kafka
by Vladic Ravich
Illustration by Tony Millionaire

Consider the Mort

Vladic Ravich
10 Snaps

For a salmon in Canada, the fish harvest ends with a slippery slide through one of five black chutes. Halfway down, a piston squeezes out a puff of exhaust as a pneumatic hammer strikes the fish on the back of the head at more than sixty miles per hour. The salmon slides sideways onto the bleeding-table, its visible eye unnaturally still. That’s how you know it’s stunned, explains Jason Stalker, the harvest master for Marine Harvest, a multinational aquaculture company in Campbell River, British Columbia, that slaughters thirty thousand fish every day. Now the salmon is ready for a quick cut of the gills, through which blood is pumped out of its body by a still-beating heart. The fish are dead before coming to, and, silent as loaves of bread, they push one another into the freezer in the ship’s hold.

The salmon harvest begins when an “air stone” is put into the water at the front of the trough, which is a huge pocket of netting where a few thousand salmon are slowly being corralled. The air stone releases a surge of bubbles that creates motion in the water, and the salmon turn to face it, riding the current. “You see, they’re lined up good, like firewood,” Stalker points out. One by one, the fish are sucked through a tube and into the minivan-sized SI~5 stunner bolted to the stern of a nearby ship.

Above the water, Marine Harvest’s Thurlow Point fish farm is little more than a grid of floating steel walkways. A few strands of rope divide the water beneath them into ten soccer field–sized pens, and the only structure is a fish-feed warehouse. The salmon are military-fatigue green, with phosphorescent scales, black spots along their backs, and slick white bellies. Every few minutes, a fish jumps across the surface of the water—there are half a million of them between nets in this stretch of ocean.

The harvest must be highly choreographed because calm fish yield higher-quality flesh. Panic in the water means bruising and a product that doesn’t last as long on the shelf. Until they’re stunned, the thick bodies of the salmon also pose a danger to the workers.

For every fifteen or so stunned salmon, one emerges from the harvest box still writhing, arching its body into a crescent and slamming its muscular tail against the table. The fish-farm workers spend the day grabbing these frantic exceptions and shoving them headfirst into a smaller manual stunner, which makes a sound like a staple gun. A few get their gills cut while still very much unstunned.

A few feet from the bleeding table, I see a bucket of “morts”: fish either dead or deemed unfit to remain with the living. A former fish-farm worker on the East Coast had told me how crucial it is to remove the morts, as they might spread parasites or disease to the entire stock—or, in the case of open-ocean farming, beyond. “After working through a few mass deaths, I became more hard-line about culling out anything unusual,” he said, asking that I not include his name or home state. “Just driving forklifts full of Dumpsters of dead and dying fish, you really want to avoid that.”

I have come to British Columbia to see what humane fish slaughter looks like, but like a hundred philosophers before me, I cannot know exactly what the still-living morts languishing in the bucket feel, if anything. In the moment, the answer seems obvious to me: what animal weighing fifteen pounds does not feel pain?

The skipper welcomes me with a broad smile and a big hand. Converting his commercial fishing boat to work with aquaculture producers was a simple business decision, but it also echoes humanity’s earliest triumphs of husbandry: he had shifted from catching fish in the wild to harvesting them on a farm.

Notepad in hand, I finally get to the question that has brought me here: is this stunner a more humane way to slaughter the fish? He pauses and looks at me, squinting, the bright December sun in his eyes. “It does make for better steaks,” he finally says. I can feel a caricature of myself being drafted in his mind. The skipper has executed and sold countless fish over the years, and like many of the estimated 200 million people in the world who make their living from fisheries and aquaculture, he either does not believe the fish can suffer or is not troubled by the question.

Growing up in New York City, I wasn’t exposed to fishing, or even to live fish, unless they were in aquariums or expiring outside a Chinatown market. I’ve caught exactly one fish in my life: watching it slap the waves with a frantic tail, I felt a rising strand of anxiety as I reeled it in. What now? I held its slimy length long enough to remove the hook and scrambled around for a rock to bludgeon it with. The aquaculture industry calls this “percussive stunning” and performs it with a machine or a black baton nicknamed “the priest.” It worked for a few minutes, until the fish flipped a foot into the air, still shamelessly alive.

We know almost nothing about the life of a salmon before it lands on our plate. Fish have physical traits we cannot fathom: imagine a line of nerves around your body that can detect electricity and shifts in the movement of water. From the perspective of a bipedal primate with only five senses, the thirty-two thousand species of fish that make up the largest and most diverse group of vertebrates are easier to describe by what they lack: no fur, no arms or legs, and not much of a face.

*

How can anyone know a fish really suffers?” asked the fisherman who gave me a lift somewhere along Highway 19. “I want to keep my life simple,” he continued, feeding a cracker with cream cheese and salmon to the old beagle resting between my feet on the passenger-seat floor.

With its netting-repair shop and harbor tight with boats, Campbell River is a fish town. Located about twenty miles south of the Thurlow Point fish farm, it is the home base for much of the aquaculture and recreational-fishing businesses around Vancouver Island. Here the Tyee (a local name for the Chinook salmon) is as much a spiritual symbol of nature as it is a smiling cartoon stenciled on storefronts—the streamlined fish consistently appears on Rotary Club signs, totem poles, and T-shirts.

The first exhibit in the Campbell River Museum is a display of Native American wide canoes, formidable clubs, knives, and great yawning hooks the size and color of sausage—all devoted to both killing and honoring the enigmatic salmon. There’s an entire wing honoring the fishing and canning industries.

Before the beginning of the twentieth century, the fishing industry involved little more than catching a meal, but as seine nets crisscrossed the waters and loggers cut into the cedar forests, the environment around the salmon became more industrial, and, in the process, people became nostalgic for what had been lost. Fishing transformed from a way to get food into a recreational industry.

The Tyee Club of Campbell River was formed in the mid 1920s with the chartered purpose “To foster interest in Canada’s greatest game fish… [and to] emphasize the ideals of sportsmanship as distinguished from slaughter.” Membership was limited to amateur anglers who had caught a Tyee salmon weighing thirty pounds or more on a light tackle.

Jeremy Maynard, known locally as “the Ardent Angler” after the title of his newspaper column, was understandably skeptical when I asked to interview him on the ethics of his sport. I asked him directly: if a fish were an eagle, would it be ethical to hook him, play him until he was exhausted, and then drown him? “Fish aren’t eagles,” Maynard said. “Salmon are tough critters. They’ve evolved to go over waterfalls.”

Yet Jeremy Maynard trains his fishing guides in how to dispatch their catch quickly. He does not use stringers, a series of hooks that attach to the face, lips, or gills and are marketed to “keep fish alive and easy to count,” and that are banned in several Canadian provinces.

In fishing, there are ethics and there is etiquette: “Without fighting the fish, there’s no recreation,” said Maynard. “There’s no sport in that.” Pain or no pain, the salmon should have a chance at escaping. “All to the end that our brave Tyee may have a fair fight” is the Tyee Club motto.

Maynard’s primary concern is with healthy populations, not the individual experiences of fish. “Without anglers, there’d be far less people taking care of streams, lakes, and habitats on a voluntary basis,” said Maynard. “None of that would take place.”

Recreational fishing brought tourists to British Columbia, along with thousands of jobs and nearly a billion dollars in business. This ensures that defenders of natural habitats can rely on an economic argument alongside their spiritual one. Just as the ancient inhabitants of this land both worshiped and slaughtered the delicious Tyee, there remains today both a love for fish and a certain lust for the sport of catching them.

Gerry Blackmun didn’t care much if I quoted him. “Screw it,” he said. “I’m retired.” Gerry spent his career at the Canadian Department of Fisheries and Oceans and performed the environmental-impact study for the estuary that once existed under the strip-mall Starbucks where I met him. “It’s just money talks and bullshit walks,” he said, referring to one or all of the fish-related industries in town. He recalled how commercial fishermen flouted their quotas and how the fish farms polluted the waters. His friend runs a tourist fishing business in town. “He’s got three big boats—takes twelve hundred bucks for eight hours and everyone gets a photograph,” Gerry said. “He’s pimpin’ his passion.” I asked if he thought fish are capable of feeling pain. “Who knows?” he said, gazing out at the four-way stop. Then he described a tool he had made—a screw welded to an ax handle—to dispatch the fish he studied for the DFO. “Pop, right on the back of the head, dead in a second.”

But like almost everyone in Campbell River, Gerry does not hesitate when it comes to his passion for fishing: “I got people dying all around me, bills to pay, I may not have a job next week, so yeah I go fishing—and it’s paradise. I play ’em, torture ’em, don’t hear them screaming, all that sorta stuff,” he said with a mischievous smile. “If I got problems in the morning, I don’t have them at night. It’s my church.”

*

Scientists cannot describe pain with the same precision they apply to the anatomy of hip-sockets or to nest-building behavior, to measuring electricity or to counting calories. We can no more quantify pain than we can measure joy or regret. For laymen, looking for signs of pain in animals is a little like separating pornography from art: you know it when you see it.

What we define as “pain” actually comprises two distinct events: the observable physical response (pulling away, screaming, grimacing) and the internal experience of anguish and awareness. We usually refer to these two components operating in tandem.

Consider the cat—or, rather, the decerebrate cat. With its cerebral cortex removed, the animal responds to stimuli with what scientists call “sham rage.” The cat will continue to bite, claw, hiss, and even arch its back, but as far as we know, the cat is no longer aware of itself. A mammal without a cerebral cortex is alive, but it is no longer a sentient, conscious being.

Consciousness, in this context, does not imply a soul—it’s something that emerges from different areas of the brain interacting. Studying “the c-word,” as one neuroscientist calls it in his presentation about the octopus brain, is always going to involve a philosophical detour. No one has yet fully explained what the c-word really is, but centuries of brain-injury cases, experiments, and other scientific flotsam make a convincing case that the cerebral cortex plays a major role in making us mammals feel like ourselves.

It is well documented that what hurts one person may not bother another, but this fact has been interpreted differently at different points in history. An article in the November 1874 edition of Scientific American ascribed this spectrum to class:

It is well known that a savage will bear pain, not merely in absolute stoicism, but apparently unmindfully, which if inflicted on a refined and cultivated individual would produce death or syncope…. Physicians state that the sufferings of childbirth are as nothing to the squaw or to the woman who constantly performs coarse manual labor, when compared with those of the delicate females of our upper classes. The same general rule applies to the lower animals.

The authors proceeded to advise against vivisections of pigs and even acknowledged that “there are many who contemplate the sport of the angler with horror and who see, in the writhings of the worm on his hook or in the struggles of his finny victim, all the tortures of human mutilation… Where then, at what particular class of being, is the dividing line to be drawn?” Good question.

In 1906, Charles Scott Sherrington conducted a series of experiments that led him to separate the concept of pain from that of nociception, which refers only to the presence of an electric signal that travels through a nerve and causes a physical response. Leeches, worms, slugs, and fruit flies all demonstrate nociception, but that does not mean they are capable of experiencing these signals as pain.

While teleost (boned) fish have nociception roughly similar to our own, some other aquatic animals do not—nociceptors have not been identified in sharks and rays. Perhaps they evolved an alternative method of self-preservation, or maybe they have more to gain from recklessness than from caution.

Pain serves varying essential evolutionary purposes and so is experienced by species in different ways. If a zebra fails to ignore a harmful situation or stay off a bruised bone, it’s not going to last long. However, organisms as primitive as bacteria will retreat from harmful chemicals—that does not mean they are actively suffering.

Even Peter Singer, whose philosophical work aims to extend our ethical awareness to include animals, admits that oysters may not deserve a blip on our ethical radar. They have two nerve centers, do not move, do not have a central nervous system, and lack anything analogous to a brain.

But Singer has no doubt that fish feel pain: “Surely, it is only because fish do not yelp or whimper in a way we can hear that otherwise decent people can think it a pleasant way of spending an afternoon to sit by the water dangling a hook while previously caught fish die slowly beside them.”

Fish have nerves and spines and brains, but there is no consensus on whether they are capable of suffering. In his far-ranging 1991 essay “Assessing Pain in Animals,” Patrick Bateson writes that veterinarians trying to create a framework for measuring pain in animals “more or less give up in despair when they get to fish.”

The International Association for the Study of Pain (IASP) defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” Simple enough, but this widely cited definition is a sort of philosophical iceberg because it is followed by a footnote seven times its length. Pain, the footnote concludes, “is always a psychological state, even though we may well appreciate that pain most often has a proximate physical cause.”

In this light, consider the human fetus. On the last day of March 2012 the state of Georgia passed a law that criminalized abortion after twenty weeks of pregnancy, based on the claim that a human embryo has the capacity to feel pain at this point. Experts overwhelmingly disagree with this cutoff, arguing that the neural pathways necessary for feeling pain appear, at the earliest, at twenty-four weeks. Others argue that a conscious experience of pain does not develop until much later. “Pain is always subjective,” says the IASP footnote. “Each individual learns the application of the word through experiences related to injury in early life.”

Human survival depends on the ability to live together. We read each other for signs of pleasure and pain. What’s the purpose of the excruciating pain caused by a kidney stone lodged in the urethra, asks Bateson in his essay. “Is a person writhing in agony on their back more likely to recover than somebody who feels nothing?” Only if someone else reads his pain and remembers a cure.

Consider the toddler who falls onto his knees on the playground. He looks for his parent’s gaze before bursting into tears. Bateson hypothesizes that human pain may have evolved as part of our inherited social skill set. The more we care for one another, the more likely we are to keep our kin alive and pass these traits on to the next generation, just as the miserable narrator of Dostoevsky’s first novel, Notes from Underground, understands that the moans of a person afflicted with a toothache are a public act: “He knows himself that he is doing himself no sort of good with his moans… The injured man cries out for others to hear him.”

That’s not to say that being a highly social species is the sole benchmark of mental complexity. If it was, ants and bees might be having a similar debate about us. Instead, human self-awareness emerges from our unique brew of mental abilities, which includes extensive memory, fine-motor control, an unparalleled capacity for abstraction, and complex language.

Perhaps suffering is just a product of the human urge for narrative. When we look at art, for example, its effect relies on the experience of the viewer. How effortlessly we attribute ecstasy to the painted gold eyes on a rectangle of cloth or weave a plot into nothing more than a progression of musical chords. Remember your favorite stuffed animal—didn’t you once think it had the capacity to suffer?

In our minds, our lives unfold like the stories we read in novels or impose on the constellations. This sense of narrative, this desire to suss out meaning, may be the essence of suffering. Maybe this desire for narrative explains the difference between reacting to negative stimuli and actually feeling pain. We recall how we felt before experiencing pain and reflect on its source and the injustice of the situation. Without language, without theory of mind, without self-awareness, without mirror neurons and the rest of our unfathomably complex neuro-knot, perhaps there really is no suffering?

In the four-million-year-old fossil record of our closest ancestors, the hominid species, only human beings and Neanderthals show evidence of using symbolism, ornamentation, musical instruments, figurative/abstract representation, and performing burials. No one knows if this aesthetic sense is a distinct ability or a sliding scale, but, left to their own devices, chimps don’t make cave drawings.

Of course, all of this might strike you as nonsense. Equating the ability to experience suffering with consciousness may be its own form of anthropocentrism. Maybe a lack of self-awareness gives the pain a monopoly over the senses?

*

With more than forty years as a neuroscientist and a lifetime as a fisherman, Dr. James Rose, a professor emeritus at the University of Wyoming, has spent the last decade spearheading the movement against the increasingly popular notion that fish feel pain. Why should we apply human concepts of pain to fish, he argues, when our understanding of their subjective experience is almost nonexistent? Rose—like almost every expert in the fish-pain debate—is weary of the press. As we drove to a café near his home in Fort Collins, Colorado, he kept a hand on his closely cropped white beard and chose his words carefully.

There was a time when an American scientist would feel about as comfortable discussing suffering in fish as debating whether fish have souls. This attitude once dominated the study of animal behavior and psychology. Rose’s critics compare him to Burrhus Frederic Skinner, the founder and chief enforcer of the “behaviorist” school of psychology. Skinner is regarded as something of a bogeyman in the popular imagination for his obsession with learning to control behavior and experimenting on animals. However, Skinner’s mission was actually to direct psychological research toward experiments with measurable, tangible results. He believed in ignoring the inner world of animals in order to test concrete hypotheses that did not require the interpretation and measurement of animal feelings. Skinner did not deny the possibility that animals have feelings, but he described their inner world as a “black box” that was impossible (and bad for your scientific career) to explore. His research into basic psychological concepts like reward and punishment spawned an entire field whose discoveries have been put to use in everything from political campaigns to rehab programs.

Skinner’s dismissal of experiments into animal subjectivity has fallen out of favor. After the “Cognitive Revolution” of the 1950s and ’60s, the so-called behaviorists began to lose ground to researchers who ignored Skinner’s methodology for practical reasons (such as the study of artificial intelligence), and to those who were simply eager to dive headfirst into the “black box” and design experiments that could discern elusive traits like self-awareness.

Many of the most creative contemporary experiments allow these subjective interpretations to creep into their vocabulary—or at least into their press releases. Studies get wide coverage for finding evidence of empathy in rats when they’ve shown only “social mediation of pain sensitivity.” The anthropocentric explanation is tempting: experiments claiming that animals have empathy or envy or cunning get scientists attention and science reporters an angle.

“Emotion has happened,” wrote New York University neuroscientist Joseph LeDoux in a 2012 paper for Cell magazine. Using PubMed, he found about one hundred papers published during the 1960s with the word emotion in the title; there were more than two thousand in the last decade. But even as he contributed his own theories for this phenomenon, LeDoux called for skepticism: “Research on the neural basis of feelings in humans is in its infancy. We will never know what an animal feels. But if we can find neural correlates of conscious feelings in humans… and show that similar correlates exist in homologous brain regions in animals, then some basis for speculating about animal feelings and their nature would exist. While such speculations would be empirically based, they would nevertheless remain speculations.”

Rose worries that public perception has been swayed by an “irritating wasteland” of pop-science cable shows and articles that depict animals as creatures that look different but share our particular range of feelings. He calls this “trophy-hunting”: the ape that learned sign language, the rats that forgo chocolate when given the chance to open others’ cages, the parrot that can use language to pick the right object. Then there are the weekly news stories about hero dogs and painting elephants, not to mention the YouTube videos.

Rose is proud to be “old-school” and thinks many contemporary interpretations show that caution has eroded. He does not claim animals are automatons, but he represents a significant number of scientists who roll their eyes at the latest functional MRI study claiming to show that we “love” our cell phones, or that animals “befriend” one another. For these scientists, these terms are misleading in human subjects, and simply wrong when applied to animals.

When asked why, five years into his retirement, he continues to publish papers that challenge the idea that fish feel pain, Rose says he doesn’t want future generations to stop fishing or restrict medical research using fish. His fear that the next generation may avoid fishing is well founded. Whether the cause is squeamishness or video games, the internet or the economy, many rural parts of the country have seen double-digit declines in hunting and fishing licenses in recent decades.

Animal-rights activists enthusiastically encourage these trends—for them, experiencing nature does not necessitate role-playing predator and prey. “Kayaking does not involve inflicting unnecessary pain on animals,” said PETA spokesman Ryan Huling. “[Rose’s] sentimentality of things like fishing is very representative of an older generation. PETA intentionally focuses our campaigns on reminding young people that animals have personality and should be respected.”

*

There is one difference between mammals and fish that pushes Rose beyond skepticism: he argues that because they do not have a neocortex, fish do not meet the minimum operating requirements for consciousness. Also called the isocortex, this outermost layer of the brain is associated with many of the higher mental abilities of mammals. The prefix neo implies an additional, evolutionarily upgraded part of our anatomy.

The neocortex makes up nearly three quarters of the human brain. It is densely packed and has six layers that integrate with each other and the rest of the brain. This back-and-forth communication throughout and between layers is believed to contribute to our moment-to-moment conception of reality—our conscious experience.

“The fish pallium, compared to the neocortex, contains far fewer distinctive neuron types, neurons with less structural complexity, far less-ordered connections, less thickness, a paucity of internal connections, and no space for them, anyway,” Rose explained. Mammals have far more “association cortical areas” than fish. These are areas that do something other than control movement or process sensory data. They are often assumed to be essential for abstract thought. Without these areas, Rose argues, fish lack the “cross-cortical integration” essential for consciousness. For him, a fish is like a reference library full of books but with no librarian present. From this perspective, the question “Do fish suffer?” presents the same pitfalls as asking “Do fish love their offspring?” or “Do fish have a favorite hour of the day?” While they may have a vast range of emotions, they lack the neural integration to experience these emotions as they occur.

Halfway around the world, a lab in Spain is making the opposite argument: “The fish pallium is far [from] simple or undifferentiated,” said Dr. Cosme Salas Garcia, a neuroscientist at the University of Seville. “Conversely, it shows a high degree of complexity and it displays a functional organization that is surprisingly comparable to the mammalian isocortex.”

Dr. Naoyuki Yamamoto, a biologist studying the neuroanatomy of fish at Nagoya University, in Japan, agrees that the forebrain of the fish is not “laminated”—which is to say interlinked in three dimensions—in the same way as the mammalian neocortex is, but this does not mean it cannot function in a similar way. He readily admits that his own hypothesis—that the sensory-processing areas of the fish brain correspond to the neocortex—is not yet proven. Even though he disagrees with Rose’s assessment, Yamamoto does not think the issue is settled. “It may be frustrating,” said Yamamoto, “but I think it is risky to make a conclusion with inadequate data.”

Fish have been documented building nests, recognizing other individual fish, and living in communities with social hierarchies. Some species form monogamous relationships; others learn from other fish; some remember scents for years; others use tools. Some even develop specific traditions that vary among different schools of fish within a single species.

So how can fish accomplish these complex and cognitively demanding behaviors? Perhaps in the same way our bodies orchestrate our heart rate, breathing, hormones, and countless other processes: unconsciously. When we run for the bus, we are virtually unaware of the exquisite adjustments necessary to keep our balance.

Say consciousness is like a car, and the human neocortex is a particular feature of this car, like a fuel injector. Bumper cars don’t have fuel injectors but they’re still a kind of car. Or perhaps the neocortex is more like a car’ steering mechanism. Any vehicle without one is basically a train on a track, not a vehicle you can drive. For Rose, fish are a “largely brain-stem-mediated organism.” They can move as fast and far as other species, but there’s no one behind the wheel.

One way to speculate on the role of the mammalian neocortex is to compare its size to the rest of the brain. Mammals that live socially tend to have large neocortexes, and their relative size is an indicator of the size of their social group and how much they interact. Perhaps this is true for the forebrain of the fish as well. Perhaps the criteria for determining sentience depend less on species and more on how important your sense of self and of others is to your survival.

“It may be that some other species have an ‘alternative’ type of consciousness,” said Rose. But this consciousness would be the result of that species’s brain structure and might not include the capacity for suffering.

“The other side talks about giving fish ‘the benefit of the doubt,’” Rose said. “That just means, ‘We don’t know if something is true, but we feel compelled to believe it as if it is true.’”

In 2002, the year in which Rose published his paper titled The Neurobehavioral Nature of Fishes and the Question of Awareness and Pain, scientists in the United Kingdom began a series of experiments to systematically build the case that fish experience pain. Victoria Braithwaite, Michael Gentle, and Lynne Sneddon published the results of three experiments that moved the debate from obscure scientific journals into headlines around the world.

They asked two questions. Do fish have the neurological “hardware” to perceive pain? And if so, do fish behave like they are in pain?

In her book Do Fish Feel Pain? Braithwaite describes how Sneddon carefully removed the skin and bone from the head of an anesthetized trout. She sliced off cross sections one thousandth of a millimeter thick from each of the three branches of the trigeminal nerve. Under a microscope, these branches resemble an overhead view of a dried riverbed filled with rocks whose circular outlines have been dyed blue. These circles are the same tiny A-delta and C fibers that signal pain in human nerves.

A-delta fibers have a fatty coat of insulation, allowing them to relay signals quickly. Their activity spikes immediately after an injury occurs. When you strike your finger with a hammer, A-delta fibers are the first trigger to yank your finger away. The dull, throbbing, long-lasting pain is generated later by the thinner, slower C fibers.

Sneddon found far fewer C fibers than A-deltas in fish. While mammals have 60 to 80 percent C fibers (and 20 to 40 percent A-delta fibers), the trout had only about 5 percent C fibers. While Braithwaite calls this a “mystery,” Rose sees it as one of many overlooked questions surrounding her experiment.

Humans born with congenital insensitivity to pain are unresponsive to severe injuries like broken bones and burns. This defect is characterized by having less than 28 percent of the normal number of C fibers—still far more than trout have. Rose also notes that sharks—who have not been found to possess A-delta or C fibers—behave like trout when they are hooked. Why attribute this similar behavior to pain?

Sneddon cautions against applying mammal-like properties to these fibers. Insulated or not, they are just wires for passing a signal—it’s the brain’s interpretation of the signal that ultimately matters. Perhaps fish have evolved a different use for their A-delta nociceptors, she suggests.

The next part of Snedden’s experiment was intended to show that these nerves convey information to the brain. The trout was anesthetized and placed in a custom-built cradle that kept it in an upright position. With tubes and pumps continuously flushing its exposed skull, Sneddon looked into the upturned face of the trout and measured the signals that went from face to nerve to brain and concluded that they are analogous to the signals in mammals.

Rose and Sneddon agree that arguments based entirely on anatomy are limited. To argue about whether fish feel pain, one must study how fish behave in response to experiments that could potentially cause pain. Sneddon’s next experiment involved injecting different groups of trout with potentially painful substances (vinegar and bee venom) and comparing their behavior to that of a control group injected with a benign saline solution. The results encouraged their next and most ambitious experiment. To demonstrate real pain, they needed to show that something was happening beyond mere nociception—a reaction more involved than a physical reflex. This time they repeated the injections with three more groups of trout, each placed in a tank with a colorful LEGO block in the middle. Relying on the trout’s well-known aversion to new objects, they wanted to see how the injections would interfere with the trout’s natural inclination to avoid the block.

The fish that got the saline injection responded as expected: they avoided the new object. In comparison, the ones that were injected with the vinegar or bee venom spent more time closer to the LEGO block. The researchers interpreted this as evidence of a changed state of mind.

The publication of these studies caused a media sensation. The skeptics immediately began publishing critiques, but Sneddon’s advocates were no less outspoken. Headline writers let loose their best ichthyologic puns: anglers were “hooked” and the question was “slippery.” Suddenly, fish felt pain.

“The issue is that the [Sneddon] paper garnered much media attention and the majority of outlets failed to give it a critical look,” said Dr. Steven Cooke, a fish expert at Carleton University who has published papers with both Sneddon and Rose. “The paper is not very balanced in perspective.”

Rose and six coauthors published their latest appeal for skepticism in December 2012, arguing that “fish are unlikely to experience pain” and “much of this research seems mission oriented and differs, accordingly, from the more detached tradition expected of basic science.”

While the two camps continue to duke it out, their fundamental disagreement has been ongoing at least since the ancient Greeks began debating the home of the soul. No one disputes that nociception can be measured, but there is no formula for converting a physical response into a subjective experience.

“Rose’s opinion is that [fish pain] has to be identical to human pain for it to be pain,” wrote Sneddon in an email, summing up just how irrelevant his perspective is to her camp. “As neither of us have ever been a fish we really do not know what a fish feels so one cannot definitively prove 100% that any animal suffers.”

Sneddon and dozens of other researchers continue to publish reviews and experiments that have traced the pain signal to the higher-function areas of the fish’s brain, further supporting their argument that potentially pain-causing experiences do affect the well-being of the fish on a subjective level. Braithwaite has, perhaps unsurprisingly, teamed up with a philosopher to design further experiments.

*

While the debate about fish pain continues to rage, the demand for fish as food—especially in the developing world—has skyrocketed, putting ever more pressure on already-dwindling stocks of wild fish. According to the European Union, fish farming is one of the world’s fastest-growing sectors of food production, currently accounting for nearly half the fish eaten worldwide. Farmed fish are certainly more stressed than free fish: this is manifest in changes to their breathing, spikes of hormones in their blood, and their movements.

Debates over the suffering of fish depend as much on cultural perspective as on science. In Canada, operating procedures at fish farms have become increasingly uniform, bringing vast improvements in the salmon’s well-being. Scotland has implemented humane-harvesting laws. Switzerland has limited catch-and-release fishing on ethical grounds, and in the United Kingdom a pet store was charged for selling fish to a minor. But in the United States, regulators and industries do not discuss humane slaughter. Fish—along with reptiles, amphibians, and invertebrates—are not covered by the Animal Welfare Act.

“We’re a bunch of troglodyte cave people on this,” said Dr. Fred Conte, a professor at the University of California at Davis who works closely with aquaculture producers. We spoke for many hours about the eyes of sturgeon, the challenges of hydroponics, the fear of regulations, the unsavoriness of certain aquarium manufacturers, and, of course, the question of fish and pain. “The industry has so many problems going on in the United States right now that fish welfare is just not their top priority,” said Conte. “They are in a reactive mode, not a proactive mode.”

Conte is no activist—he lowers his voice and literally looks over his shoulder before he mentions “those animal-rights people.” But he says that when he brought up fish welfare at a California Aquaculture Association meeting in the 1990s, the room went silent. “It was like I had released a skunk in the room. People chuckled.”

Still, even in the United States, concern over the welfare of chickens and cattle has begun to drive consumer demand, and fish welfare may be the next concern. Industry surveys show a consistent consumer interest in “humane treatment,” although that interest declines when humane treatment leads to higher prices. “Social pressures will push changes faster than the science,” said Conte. “The bottom line will be the ringing of the cash register.”

The new battle is over whether to call negative biological indicators “stress” or a danger to “welfare.” A codified concept of fish welfare could be enough to spawn a threat to the existence of recreational fishing, an industry Conte estimates to be twenty times larger than aquaculture. “And who supplies their fish?” he said, referring to the aquaculture industry. “Any attack on [recreational fishing] is an attack on [aquaculture’s] customers.”

The situation in Europe could not be more different. By 2004, the European Union had imposed legal requirements for the welfare of farmed fish, recognizing that “many existing commercial killing methods expose fish to substantial suffering over a prolonged period of time.” On January 1, 2013, a new EU protocol came into force, requiring that animals (including fish) “be spared any avoidable pain, distress or suffering during their killing and related operations.”

“One way to see it is that fish were recategorized as an animal,” said Dr. Marianne Elisabeth Lien, a Norwegian social anthropologist researching the domestication of fish. Norway, by far the largest producer of farmed fish in Europe, has protected their welfare since 1974. By 2012, percussive and electrical stunning was the only legal means of harvesting fish there.

Commercial fishermen have no economic incentive to consider the suffering of their fish. Wild-caught fish die in dramatic ways: they asphyxiate, their internal organs explode, they struggle for hours on hooks and lines, nets snare their sensitive gills—and all this happens on an industrial scale. It takes just minutes to haul nets packed with thousands of fish onto a boat. If these were cats or dogs, the whole operation would be prohibited. But of course fish are not cats and dogs. Fish are like evolutionary cousins who moved away long ago: we don’t give them much thought.

Aquaculture is not immune to charges of cruelty either, though it has embraced fish welfare because it helps the industry’s bottom line. A torrent of research has emerged to figure out how to keep newly domesticated aquatic animals healthy while still turning a profit. The results have been mixed. In his 2009 book, Eating Animals, Jonathan Safran Foer titled the chapter about aquaculture Our Underwater Sadism, pointing to infestations of sea lice that “sometimes eat down to the bones on a fish’s face” and translating the vocabulary of fish-welfare research with the zeal of a prosecuting attorney.

According to Foer, fish farms’ assessment of welfare comprises one euphemism after another. Concepts like “water quality,” “crowding,” “handling,” “disturbance,” “nutrition,” and “hierarchy” actually mean filthy water, crowding so intense that animals begin to cannibalize one another, handling so invasive that signs of stress are evident the next day, fish that are unable to flee from the predators that surround their pens, nutritional deficiencies that weaken their immune systems, and an inability to form a stable social hierarchy, resulting in more cannibalization.

This list of atrocities may well apply to some fish farms, but a visit to a modern, well-run facility makes domestication seem like a series of trade-offs, not unlike those we make in our own lives. One could portray New Yorkers, for example, as choosing to inhabit a series of overcrowded cells, with drug addicts, broken families, murderers, and suicides on every block. They breathe poisonous air, produce mountains of waste daily, regularly get hit by cars, and rarely see the stars.

*

One night I visited two graduate students at the Columbia University Med­­ical Center who were conducting experiments on a new brain-imaging technique. To calibrate the process, they paralyzed an elephant-nose fish and left it under a microscope for hours. It remained awake until it expired. This experiment could not be conducted on mice, but the university’s ethical guidelines permitted fish to be used. There is no consensus on why, but this policy illustrates how much improvisation is involved in applying ethical guidelines. “There are no regulations against setting mouse traps in the basement, either,” said one of the students, “but we couldn’t do that in an experiment.”

Clear-skinned zebra fish have become one of the primary animal subjects for a vast range of medical studies. They reproduce rapidly, cost less to house than other fish, and their transparent skin allows scientists to peer inside their bodies in real time.

Not believing fish are capable of suffering, Rose opposes many existing ethical rules for using fish in research, but he is sympathetic to protecting individual animals. “We have to uphold a standard of conduct with fish, out of ceremonial respect, not something touchy-feely. We have to have respect for the organism, value it, and behave accordingly,” Rose said. For him, any unchecked commodification of fish is wrong because it prevents a meaningful connection to nature. For him, the trout, the river, and the scientific drive to know them are one and the same. “I don’t see a problem with having an ethical system to guide your relationship with other species, regardless of whether they can feel things or not. I am intensely protective of fish even though I catch them.”

Compare Rose’s view to that of Franz Kafka, a strict vegetarian who had no sympathy for even a pescatarian diet. His friend and biographer, Max Brod, recalls him standing before the illuminated tanks of a Berlin aquarium, speaking to the fish: “Now at last I can look at you in peace, I don’t eat you anymore.” Foer retells this episode in Eating Animals and observes that “fish, for Kafka, must have been the very flesh of forgetting,” eulogizing their suffering, hidden only through the carelessness of apathy.

Yet Rose’s relationship to fish is anything but apathetic. In an unpublished essay, he describes the mating process of the brook trout “according to a formula perfected in ancient ice ages, before the first flickerings of human consciousness”:

The male in my hand seems to be the same fish that I held on an August evening in northern Michigan, nearly six decades ago. I stood in that small stream, feet numbed from wet-wading the spring-fed current and beheld a male Salvelinus fontinalis: humped back and hooked jaw. Red spots with blue haloes dotted the flank beneath the lateral line. Below these spots, along the side of the belly, ran a blood red and fire orange band. This brilliant color merged with a streak of black and then the white-gray of the belly’s bottom. It was the most beautiful thing I had ever seen: a living jewel, illuminated in the failing light of evening. I looked up at the sky above the swampy meadow and realized that the color of the sunset was the color of the fish. They were identical. I was holding the sunset in my hand.

So who exactly is anthropomorphizing the silent fish? Are they just a blank canvas for our own personal narrative? Is the fish even really silent? Comedian Mitch Hedberg joked that “fish are always eating other fish. If fish could scream, the ocean would be loud as shit.” Well, according to a 1968 study in the Russian-language Sounds of Fish Atlas, the European weatherfish—which looks like an eel with a snail’s head—does scream.

Or, rather, its swimming bladder produces a unique half-second vibration between zero and four thousand hertz when the skin on its back is pierced.

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