Do fish feel pain?

Do fish feel pain when we hook them? Not according to Dr. James D. Rose.
And before you think that Rose is a “quack” or paid parrot of the fishing industry, be advised he is a respected professor of zoology and physiology at the University of Wyoming, where he has studied neurological issues for 30 years.
In a paper Dr. Rose presents in the Reviews of Fisheries Science, he says just because we feel pain when we jab a hook into our fingers, we shouldn’t assume a fish feels the same sting.
It does not.
Rose says pain is a double-edged psychological experience with perceptual and emotional components. The perceptual component tells us we’ve been injured. The emotional aspect is the pain that follows after we realize we’ve skewered ourselves.
Rose also is quick to point out that not all injurious stimuli lead to pain. He uses the example of going to the dentist for a filling. The dentist freezes the affected tooth.
When the tooth is drilled, Rose says, “the sensory nerve cells that would normally trigger pain are still excited, but the nerve block prevents activity in these receptors from being sent to the brain, so pain is not felt.”
Dr. Rose cites other examples of people enduring pain without any discomfort as a result of certain head and spinal column injuries.
Still, the bottom line is that most of us feel pain when we react to what Dr. Rose calls “nociceptive stimuli.” For example, jabbing ourselves with fishhooks and nicking ourselves with knives.
But fish do not, he explains. “Fish have the simplest types of brains of any vertebrates while humans have the most complex brains of any species.
“Conscious awareness of sensations, emotions, and pain in humans depends on our massively-developed neocortex and other specialized brain regions in the cerebral hemispheres.
“If the cerebral hemispheres of a human are destroyed, a comatose, vegetative state results.
“Fish, in contrast, have very small cerebral hemispheres that lack neocortex. If the cerebral hemispheres of a fish are destroyed, the fish’s behaviour is quite normal because the simple behaviors of which a fish is capable (including all of its reactions to nociceptive stimuli) depend mainly on the brainstem and spinal cord.”
It is heady stuff, no pun intended, but the distinction Rose makes between human existence being “cerebrally-dominated” while a fish’s existence is “brainstem-dominated” is fascinating.
In plain words, he uses the example of a fish still seeing things quite normally even after researchers remove the little gray matter in its noggin. Do the same to a human, of course, and we’d be blind.
Portions of our brains, says Dr. Rose, generate the experience of pain that we feel. But since these same regions don’t exist in a fish’s brain, the walleye, bass, perch, or crappie on the end of our line doesn’t have the capacity to experience the same unpleasant feeling.
I know what you’re thinking. Maybe a fish feels pain, though, through some other mechanism? Or, as Rose puts it, “generates the psychological experience of pain by a different process than that occurring in the frontal lobes of the human brain.”
The argument is insupportable, says Dr. Rose, “because the capacity to experience pain, as we know it, has required the massive expansion of our cerebral hemispheres, thus allocating large numbers of brain cells to the task of conscious experience, including the emotional reaction of pain.
“The small, relatively simple fish brain is fully devoted to regulating just the functions of which a fish is capable. A fish brain is simple and efficient, and capable of only a limited number of operations.”
Okay. But what about when a fish leaps out of the water or struggles when we hook it. Surely those are signs of pain? Absolutely not, says Dr. Rose.
“It should be clear that fish behaviour is a result of brain stem and spinal patterns of activity that are automatically elicited by the stimulation of being hooked, but that fish don’t have the brain systems necessary to experience pain,” he explains.
“It is very important to note that the flight responses of a hooked fish are essentially no different from responses of a fish being pursued by a visible predator or a fish that has been startled by a vibration in the water.
“These visual and vibratory stimuli do not activate nociceptive types of sensory neurons so the flight responses can’t be due to activation of pain-triggering neural systems.
“Instead, these flight responses of fish are a general reaction to many types of potentially-threatening stimuli and can’t be taken to represent a response to pain.”
Amazingly, Dr. Rose says that not only does a fish’s struggle on the end your line have little to do with feeling pain, it has nothing to do with fear, either.
“The brain regions known to be responsible for the experience of fear, which include some of the same regions necessary for the emotional aspect of pain, are not present in a fish brain,” he notes.
“Instead, these responses are simply protective reactions to a wide range of stimuli associated with predators or other threats, to which a fish automatically and rapidly responds.”
While a fish may not feel human-like pain or suffering, Dr. Rose says they do, however, secrete stress hormones when they’re chased by an eagle, osprey, bear, or bigger fish, or hooked by an angler.
And these stress hormones can have undesirable health effects on the fish if large enough amounts are allowed to build up. That is why Rose says it is important to land fish before they’re exhausted, keep them in the water, and release them as quickly as possible.
Do those simple things, Rose says, and you can sleep as peacefully and guilt-free at night—as the fish you hooked and let go.

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