Do Fish Feel Pain?

The debate over the ability of fish to feel pain is quite intense within the scientific community and I’m going to do my best to summarize the slew of available research on both sides. I have to be honest, going into this video I figured I’d read a couple articles and write up a script. Two days later, I was still reading. I like to keep my video posts as short and simple as possible. But I also don’t want to skimp on the facts. So get ready from some hardcore, scientific truth bombs. [tweet this]

This video post is the first in a series I’ll be doing on fish and other marine life. Before we look into whether or not fish can feel pain, we must first understand pain itself. This is a tall order- scientists are constantly learning more about the nature of pain and there are still a lot of unanswered questions. But I’ll do my best to simplify this extremely complex topic.

The International Association for the Study of Pain has defined pain as:

“An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage with the conditions that, one: pain is always subjective; and two: pain is sometimes reported in the absence of tissue damage; and three: the definition of pain should avoid tying pain to an external eliciting stimulus.”

These last points are of grave importance within the fish pain debate, so I’ll briefly elaborate.

One of the most critical concepts about pain is the distinction between nociception and pain. when you cut your finger, that stimulus activates your nociceptors, which are receptors of sensory neurons that respond to potentially damaging stimuli by sending signals to your spinal cord and brain. Nociceptors are often incorrectly called pain receptors. While the message they convey can be interpreted in the brain as pain, nociception itself can occur without pain. Nociception is a purely neurological occurrence, but pain perception is largely psychological and emotional.

To illustrate the distinction, if you’re under anesthesia during surgery, your nocicpetors will still be firing and carrying signals to the dorsal horn of your spinal cord where a reflex response is triggered and the signal moves on to the brain to be interpreted. However, as you’re unconscious while under anesthesia, you cannot interpret these signals as pain and thus do not experience pain.

Neuroscientist Patrick David Wall, the world’s leading expert on pain, clarifies that “activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain” as pain “is always a psychological state.”

Therein lies the rub with the fish debate. In his article, The Neurobehavioral Nature of Fishes and the Question of Awareness and Pain, which has become the go-to resource for the “fish don’t feel pain camp,” Dr. James D. Rose argues that because fish lack a neocortex—a neuroanatomical structure that, in humans, is associated with conscious awareness—they cannot feel pain.

He explains fishes’ response to and avoidance of noxious stimuli, such as electric shocks, are simply unconscious, reflexive responses. Nociception goes way back on the evolutionary timeline, existing in some of the earliest animals possessing nervous systems. Sea anemone, corals and jellyfish, for example, all possess nociception.

Rose compared fishes’ avoidance of noxious stimuli to the involuntary contorted facial reactions displayed by neocortically damaged humans who possessed no consciousness yet would grimace in a way we associate with pain when stimulated.

Rose argued that because fish lack the conscious awareness of their nociceptive cues due to their absence of a neocortex, they cannot feel pain. This distinction between pain and nociception seems to take down any claim of fish pain perception predicated on their avoidance behavior and possession of nociceptors.

However, Rose’s stance isn’t as foolproof as it may appear. Dr. Stephanie Yue in her report Fish and Pain Perception, points out that one of the major flaws in Rose’s argument is the fact that it hinges on the neocortex being “the sole means by which pain can be experienced, ”which “suggests that it is the seat of consciousness.” She goes on to state:

“A cursory review of the neurobiology of consciousness shows both the complexity of the phenomenon of consciousness and that conscious phenomena, such as pain, are not restricted to any one location in the brain. … [T]he neocortex is unique to mammals. Were the presence of a large, considerably developed neocortex the requirement for experiencing pain, as Rose suggests, his theory would eliminate birds, amphibians, other non-mammalian animals, and even some mammals from having the capacity of feeling pain, which is unfounded.”

In short, comparing a fish or any other different species to our own rather than attempting to understand their unique physiology is greatly flawed, especially when the neuroanatomical aspects of our own consciousness are still so unknown. This kind of cross-species application is the main flaw of the animal testing model as well.

Check out this video post in my animal testing series to see how humans are often harmed and even killed by medications that made it through animal trials.

Now in reality, the brain of fish isn’t even quite as foreign from ours as Rose would have us think. As Yue points out:

“[R]esearchers have found many similarities in neuroanatomical structure between fish and land-based vertebrates, from gross regional structures to finer neuronal structures, and neurobiological evidence proposes that there is strong structural conservation throughout evolution.”

For the sake of time and to keep this as simple as possible, I’m not going to delve into the specific similarities in brain structure and function between fish and mammals.** If you want to get into the scientific nitty-gritty, which I highly recommend, see the resources down below and the extra bit with the double asterisks pertaining to this point in particular. So to my fellow nerds out there, enjoy.

Just as Rose’s paper is the flagship of the “fish don’t feel pain” camp, the “fish do feel pain camp” was more or less born from a paper published by Lynne Sneddon, Victoria Braithwaite, and Michael Gentle in 2003. It’s strange, really, that it took that long to look into this matter.

In her book Do Fish Feel Pain?, Braithwaite, suggests that the delay was perhaps because “asking if fish feel pain challenges established ideas; it is akin to opening the proverbial can of worms—as we pose the question, a whole slew of unknowns arise.” When preparing for their initial research paper, she says she and Gentle wondered, “Could this be right? was it really the case that at the end of the twentieth century we couldn’t answer a straightforward question about whether fish had the necessary gross anatomy to detect pain? fish are the largest vertebrate group. did we really know so little?”

Within their initial study, the three scientists injected bee venom or vinegar around the mouth of fish and recorded their reactions. The fish had increased breathing rates, lost interest in food, and would rub the injection sites up against the glass of the tank.

I’d like to take a moment here to talk about this kind of animal testing. While the scientific exploration of animals’ experience is fascinating and can help convince people that animals do feel and deserve protection, it’s never justifiable to harm, torture and kill animals in the name of intellectual progress. Because they do not consent to participating in such studies as human trial participants can, the practice is not ethical. I’ll circle back to this matter when I wrap up but I just wanted to make a note as I’ll be relaying results from such studies.

Immediately after publishing, Braithwaite and her colleagues were grabbed up by the media who all wanted to know whether this meant that fishing, or angling, was cruel: Did fish suffer from this “sport”? Unfortunately, this study did not answer that question as it didn’t delve into the perception of pain, the level beyond nociception. To do so, Braithwaite says they needed to incorporate complex behavior. They chose a trout’s natural avoidance of new things, a behavior that requires a higher order cognitive process.

Again, fish were injected with vinegar, and the control group with saline, and a new object was introduced to their aquariums. Those injected with saline showed the expected avoidance behavior while those injected with vinegar did not.

Braithwaite states, “to us these results showed that the vinegar injection was impairing the fishes’ attention, as expected if the fish experienced discomfort and pain associated with the vinegar treatment.” To be sure, they repeated the experiment, only giving all the fish a dose of morphine along with their injections. As predicted, when given pain relief, the fish injected with vinegar resumed their normal avoidance behavior

Braithwaite summarizes: “The fish must be cognitively aware and experiencing the negative experiences associated with pain. Being cognitively aware of tissue damage is what we mean when we talk about feeling pain.”

A lesser-known Russian study published before Braithwaite and her colleagues found similar results and since the 2003 publication, a large number of subsequent studies have been conducted, finding more and more evidence of fishes’ pain perception.

While the question of nociception is separate from the question of pain, it can be further said that the question of pain may be separate from the question of suffering. So, do fish suffer?

This is again, where Rose would say absolutely not as they lack the neocortext and higher consciousness. However, these kind of statements assume that fish have to suffer as we suffer and feel as we feel or not suffer or feel at all. It’s undeniable that fish have differing physiology from us so it would be naïve to assume their cognitive and emotional abilities would be identical to ours. However, just because fish may not express themselves in a way we readily comprehend, does not mean they don’t feel pain and suffer.

Regarding this further layer, Braithwaite points to a number of other studies that delved into the cooperative interaction of fish with other aquatic animals and evidence of monitoring and self-consciousness. She states:

“Pulling the different threads together, fish really do appear to possess key traits associated with consciousness. Their ability to form and use mental representations indicates fish have some degree of access consciousness,” [tweet this]

suggesting that:

“If we already accept that mammals and birds are sentient creatures that have the capacity to experience positive and negative emotions—pleasure or suffering, we should conclude that there is now sufficient evidence to put fish alongside birds and mammals.

Given all of this, I see no logical reason why we should not extend to fish the same welfare considerations that we currently extend to birds and mammals.”

She even goes so far as to compare the evidence for fish’s ability to perceive pain to that of neonate and preterm babies, concluding that there is far more evidence of fish experiencing pain than for human fetuses. Still, sadly, Braithwaite does not take this to the full logical conclusion and still eats fish.

Something to make note of as well: Aside from the pain inflicted upon fish who are hooked and even gutted and descaled while still alive is the incredibly painful and slow process of dying from lack of water. Think about the process of drowning, how terrifying and painful it would be. Just as we cannot live without air, fish cannot live without water. And many fish that are caught are left to gasp on a bed of ice while they die a terrifying and painfully slow death.

The Humane Slaughter Act of the United States, which in and of itself is a joke, does not include any provisions for fish, poultry, rabbits or other animals outside of cattle, pigs and sheep. There is no regulation on the treatment of fish. And because it’s so easy to relegate them to a sub-animal status given how different they are from us in appearance and behavior, their deaths are absolutely brutal.

Now, as promised, to circle back to the issue of animal testing. We may be tempted to say, “but if they didn’t conduct these studies, then there wouldn’t be proof that fish suffer so more fish would be suffering.” Sadly, the proof that fish suffer hasn’t put a dent in the slaughter of fish. And the mentality of “the ends justify the means” is a dangerous road to go down. On a global scale, the United Nations Food and Agricultural organization’s data, FishCount.org.uk, estimates that we catch between 0.97-2.7 trillion wild fish every year. [UPDATED NOTE: during research for later videos, I found this number to be closer to 2.8 trillion. See here and here]

I think it’s prudent to bring forth the words of Jeremy Bentham in his text An Introduction to the Principles of Morals and Legislation published in 1789 in which he said:

“The question is not can they reason, nor can they talk, but can they suffer [emphasis added]?’ [tweet this]

Thanks for sticking with me through this research-intensive nugget.

The time it took to produce this video post clocks in at about 53+ hours. If you’d like to help support Bite Size Vegan so I can keep putting in the long hours to bring you this educational resources, please check out the support page where you can give a one-time donation or receive perk and rewards for your support by joining the Nugget Army!

For more on the dire state of our oceans, see this post, and to help explain pain in fish to kids, see this post.

— Emily Moran Barwick