For any living organism, pain is quite a complex experience to measure, even more when the subject can’t self-report. Human beings and many other mammals vocalize our pain and display other obvious pain signals, but fish simply just trash about on the end of the fishing line. This question of fish feeling pain has been pondered for decades now, so do they actually feel anything?
Before I get into it, it’s important to really understand what’s going on when we talk about pain for human beings.
According to the medical field’s definition, pain is an unpleasant sensory and emotional experience associated with tissue damage. It’s so subjective that everyone feels it differently. The key is the emotional component. In order to suffer, your brain needs wiring that lets it feel both sensation and emotion.
(Every human experience pain differently. Source)
To make the matter a little easier to understand, pain is a twofold experience, and there is a distinction to make between the conscious awareness of pain and the unconscious impulses of our nerves. The first step is the neurobiological process of our nerves communicating with the brain. That is the unconscious processing of impulses through nociception, the latter of which can also lead to complex hormonal reactions, behavioural responses as well as to learning avoidance reactions. The second step of pain is the emotional response to pain that varies from person to person.
Nociceptor nerve cells in our bodies deliver that initial pain-related communiqué along a route through the central nervous system to the brain. Research has shown that other mammals, birds and fish also have nociceptors. Sharks and rays don’t have nociceptors. The presence of those nerve cells implies that fish have the sensory capability to recognize when something is harming their bodies.
Overall, the scientific consensus is that fish have the anatomical requirements to demonstrate neurophysiologic and behavioral reactions to pain as a means of survival. Now the bigger debate in this discussion is whether or not fish actually FEEL the pain.
(Different anatomical components between the human nervous system and the fish nervous system. Source)
One of the primary arguments against fish having a feeling of pain is that their brains lack the structural elements, namely the neocortex, necessary for it. Without that, they cannot be aware of the pain as they are experiencing it. There is little evidence that exists to suggest that the fish also react emotionally to pain like humans. The physiological prerequisites for a conscious experience of pain are hardly developed in fish.
Others have argued that fish could still have consciousness without a neocortex, and some other researchers believe that animal consciousness could arise from homologous subcortical brain networks. They are basically arguing that fish may feel pain through a different structural element than humans. Yet others believe fish have the same intelligence as other animals.
(One of the many PETA campaign posters against fishing: “Fish feel pain just as humans.” Source: Peta)
All in all, the majority of the scientific community believes that fish can sense the pain and hence can develop avoidance behaviors (study here), but it is very unlikely that they experience it emotionally like we humans do.
- Then, why are the fish thrashing all over the place when they get caught?
It is crucial to remember that just because it looks like a painful experience to us doesn’t necessarily mean it really is pain.
Some have suggested that the animals are simply trying to escape when hooked on a line and are thrashing, darting and pulling, and they considered it an unconscious flight reaction to being pulled in a direction they don’t want to go.
This study argued that fish showed only minor or no reactions at all to interventions which would be extremely painful to us and to other mammals. Pain killers such as morphine that are effective for humans were either ineffective in fish or were only effective in astronomically high doses that, for small mammals, would have meant immediate death from shock. These findings suggest that fish either have absolutely no awareness of pain in human terms or they react completely different to pain.
Other scientists do not really believe that fish may be experience pain in their own ways. Per basic biological facts, we know it takes a lot of brain power for primates to have even primary consciousness. The odds are slim that fish can do that with a smaller setup and a very small brain.
“To propose that fishes have conscious awareness of pain with vastly simpler cerebral hemispheres amounts to saying that the operations performed on the modern computer could also have been done by the 1982 model without additional hardware and software.”
(School of Big-Eye Scad (Selar crumenophthalmus). Photo credit: Bo Pardau)
You get it, everybody is pretty divided on the topic. The debate is still ongoing and there are many papers and books written about this. We can extrapolate all we want, but until we figure out a way for fish to communicate with us, this discussion will probably remain unsettled.
Consequently, the take-away message here is that it is very difficult to deduct underlying emotional states based on behavioral responses, especially based on human standards of pain.
In any way, anthropomorphizing fish doesn’t solve their biggest problems, which really don’t have anything to do with whether they have a consciousness. Rather, if we want fish around, we’re the ones who have some thinking to do about how to stop overfishing, by-catch practices and toxic pollution.