Animal rights activists have raised the question of cruelty; but there is no consensus on how to define it.
For example, if fish can feel pain when hooked, and that every fish from Johnny roaches to marlins suffer needlessly, then anglers are certainly cruel to their prey.
Gary Varner in his book “Which Animals Are Sentient” (2012) developed a list of criteria; and those animals which met all or most of them felt pain. Fish met all the criteria (nociceptors, brain, nociceptors and brain linked, endogenous opiods, response to damaging stimuli similar to humans).
Sneddon et al (2014) elaborated on Varner’s classification, dividing fish into different phylogenetic categories and adding more behavioral criteria. According to their research, bony fish (the ones commonly caught by recreational and commercial fishermen), met all standards for pain.
Commercial fishermen might claim that netting of fish is painless; and while such techniques avoid spearing or hooking, those hundreds of bluefish, mackerel, or sardines flipping and flopping around on the deck of a trawler are actually going through the agonizing death throes of asphyxiation.
In other words there is no painless way of killing fish except by drugging them in fish farms.
Given this recent, extensive, and exhaustive research, one might well conclude that fish do indeed feel pain and if animal rights activists are right, then all fishing which causes pain should be stopped.
Even if one were to accept this extreme argument, there are caveats. If fish are taken for food, then there must be some give in the cruelty argument.
There is no real ‘humane’ way for Aleuts to kill whales because no one harpoon thrust can be a coup de grace and no bullet always and unerringly finds its way into the animal’s cerebellum for a quick and painless death. Earlier tribal hunters on the African veldt wounded a wildebeest or gazelle and then tracked it for miles until, after hours, it died a painful death. Only skilled and practiced hunters can bring down an elk or antelope with one deadly shot; but there are far more amateurs out there than professional marksmen, and thousands of animals, legally hunted, die bloody and painful deaths.
This killing-animals-for-food argument would have to hold for lobsters. Throwing them into a pot of boiling water and watching them bang around the pot until dead would have to count. Sushi lovers in Japan would have to forgo their passion for fresh sushi (slices taken from still live fish).
What about oysters? All oyster-lovers know that the way to tell if oysters are really fresh is if they twitch a bit when you squeeze lemon on them. They have a nervous system and they respond, but they have no brain; so is feeling pain without making any sense of it still feeling pain?
To answer this question, one would have to go back to Descartes and other philosophers who pondered the nature of being. Some have argued that if a baby is born without sight, hearing, or tactile sense, it does not exist. Thought – sentience or consciousness – is a function of response to sensory experience. Others have argued that consciousness can precede experience, for the brain was designed to be a functioning organ per se.
Depending where you fall on the philosophical scale, you are either torturing an oyster or simply interrupting its life-cycle when you shuck and eat it. Such moral and ethical dilemmas could easily be dismissed, however, if the killing-for-food argument holds.
Things get trickier when it comes to large-scale food processing. Hundreds of millions of chickens are slaughtered each year in America alone. Cows, calves, and lambs meet the same fate. Although the owners of slaughterhouses insist that their method of killing is painless ( ‘captive bolt pistols’ deliver a powerful shot to the brain before slaughter), there are many activists who say that higher-order animals such as cows understand what is coming and suffer painful anxiety. While this may seem far-fetched, scientists are discovering new clues to animal cognition using a number of categories such as attention, selective learning and visual search and attention priming.
More important are recent studies on animals’ affective responses:
Spindle neurons are specialized cells found in three very restricted regions of the human brain – the anterior cingulate cortex, the fronto-insular cortex and the dorsolateral prefrontal cortex. The first two of these areas regulate emotional functions such as empathy, speech, intuition, rapid "gut reactions" and social organization in humans.
Spindle neurons are also found in the brains of humpback whales, fin whales, killer whales, sperm whales, bottlenose dolphins, Risso's dolphins, beluga whales, and the African and Asian elephants.
However,[researchers] Hof and Van Der Gucht clarify that they do not know the nature of such feelings in these animals and that we cannot just apply what we see in great apes or ourselves to whales. They believe that more work is needed to know whether emotions are the same for humans and whales (Wikipedia)Although these investigations have suggested that affective responses may be limited to only the highest-order mammals, researchers admit that they do not know how far down the phylogenetic scale such responses may occur.
All the more reason to stop eating meat, fish, and poultry, animal rights activists insist. Even though there may not be conclusive evidence for the pain and suffering theory of animal cruelty, why not avoid the occasion of sin?
Perhaps, but what about the Biblical reference to Man’s dominion over the animal world?
And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth (Genesis 1:26 KJV)
Certainly that provides as much moral and ethical cover for the killing of animals as any Christian or Jew could want.
Yet that passage too has been debated. God did not mean absolute, authoritarian, morally exempt dominion; but more caretaking, say activists. There is no injunction or suggestion in those words.
Genetic modification of chickens has produced animals that serve the demands of the market (oversized breasts, undersized thighs) but these birds have to be propped up until slaughtered.
Although no research has shown that this tinkering has caused specific pain, activists claim that any creature deformed so beyond God’s plan or Darwin’s evolution, would have to suffer.
Where does this leave us? It is not seem that ‘cruelty’ applies to lower-level animal species such as paramecia, shrimp, or clams; so one could continue eating them without moral concern. It is likely that higher-level organisms feel some kind of discomfort, if not pain; but no researcher has proven that a fish’s struggles is anything more than flight response, so we’re probably all right there.
Higher order animal diets are much more problematic; but beef provides a very complete, balanced, and easily assimilable source of protein; so non-vegetarians can easily squeeze under the ethical bar, especially given the captive bolt gun.
Lobsters, despite their size, have tiny brains, so one could comfortably look away from the boiling pot knowing that their thrashing about is no more than a primitive response.
The response of strict vegetarians is a good one; but the best response comes from nihilists, Epicureans, and hedonists. Life is short if not nasty and brutish. Better to enjoy it while you can. There are no social consequences other than liberal opprobrium from eating a nice broiler or T-bone. We hunt, kill, and slaughter animals because they are great on the broiler, taste good, and satisfy our hunger far more than rice and beans do. Or put more bluntly – we hunt, kill, and slaughter because we can.