Consider the lobster; pity the fish. In his justly celebrated Gourmet essay, David Foster Wallace argued that the lobster was not a mindless invertebrate, but rather a creature capable of feeling, especially pain. Wallace made his case with the brute facts of comparative neurology - lobsters have plenty of pain receptors - but also with anecdotes of the kitchen, as the crustacean resists its boiling death. "After all the abstract intellection," Wallace writes, "there remain the facts of the frantically clanking lid, the pathetic clinging to the edge of the pot. Standing at the stove, it is hard to deny in any meaningful way that this is a living creature experiencing pain and wishing to avoid/escape the painful experience."

I was thinking of Wallace's essay while reading a new paper in Animal Cognition by Culum Brown, a biologist at Macquarie University in Australia. Brown does for the fish what Wallace did for the lobster, calmly reviewing the neurological data and insisting that our undersea cousins deserve far more dignity and compassion that we currently give them. Brown does not mince words:

"All evidence suggests that fish are, in fact, far more intelligent than we give them credit. Recent reviews of fish cognition suggest fish show a rich array of sophisticated behaviours. For example, they have excellent long-term memories, develop complex traditions, show signs of Machiavellian intelligence, cooperate with and recognise one another and are even capable of tool use. Emerging evidence also suggests that, despite appearances, the fish brain is also more similar to our own than we previously thought. There is every reason to believe that they might also be conscious and thus capable of suffering."

What makes this review article so necessary is that, as Brown notes, fish are afforded virtually no protections against human cruelty. They are the most consumed animal; the most popular pet; the only creature for which it’s an acceptable leisure activity to hook them with a metal barb and then reel them, against their frantic wishes, into an environment in which they will slowly suffocate to death, drowning in air.

Such suffering is ignored because we assume it doesn't exist; fish are supposed to be primitive beasts, cold-blooded and unconscious. But Brown gathers a persuasive range of evidence highlighting our error:

Fish are exquisitely sensitive creatures, with perceptual abilities that track (or exceed) those of mammals.
Fish can learn a simple Pavlovian conditioning task - light paired with food - significantly faster than rats and dogs. They also exhibit one-trial learning: pike that have been hooked often become "hook shy" for over a year.
Fish have incredible spatial memories. Gobies, for instance, sometimes leap from rock pool to rock pool. "Even after being removed from their home pools for 40 days, the fish could still remember the location of surrounding pools," writes Brown. "This astonishing ability makes use of a cognitive map built-up during the high tide when the fish are free to roam over the rock platform."
Fish exhibit social learning. Salmon born in a hatchery can be taught to recognize unknown live prey by pairing them with fish that already feed off the prey. Guppies can pass along foraging routes; some scientists speculate that the recent shift in cod spawning grounds reflects the "systematic removal of older, knowledgeable individuals by commercial fishing."
Fish know each other. Guppies can easily recognize up to 15 individuals. If allowed to choose, fish prefer to shoal with fish they have met before.
Fish exhibit a high degree of social intelligence. "If a pair of fish inspects a predator," Brown writes, “they glide back and forth as they advance towards the predator each taking it in turn to lead. If a partner should defect or cheat in any way, perhaps by hanging back, the other fish will refuse to cooperate with that individual on future encounters." Or look at the cleaner wrasse, which removes parasites and dead skin from the surface of "client fish." Each wrasse has a large set of regular customers, who they seek to please in order to ensure return business. "If the cleaner should accidentally bite the client, then the client will rapidly swim away. But the cleaner has a mode of reconciliation; they chase after the distraught client and give them a back rub, thus enticing them to come again." Interestingly, the wrasse are far less likely to nip predatory fish, suggesting that they are able to categorize clients according to their aggressive potential.
Fish build nests and use tools. At least 9000 species of fish construct nests, either for eggs or shelter. Wrasse species often use rocks to crush sea urchin shells; they use anvils to break open shellfish. Meanwhile, cod in the laboratory figured out how to use tiny metal tags embedded in their backs to operate a feeder.
Fish rely on the same basic circuitry of nerves to process pain as mammals. This shouldn’t be too surprising: the pain receptors in all vertebrates are descended from an early fishlike ancestor. Furthermore, there’s evidence that fish also respond to pain in a “cognitive sense” – they have an experience of suffering. Brown cites a study showing that fish injected with acetic acid display “attention deficits,” and lose their fear of novel objects. Presumably, he writes, this is because “the cognitive experience of pain is dominant over or overshadows other processes.”

Brown concludes his review by arguing that fish deserve to be included in our “moral circle.” The vertebrate taxa are worthy of the same protections against wanton suffering that we offer to most land based mammals. And yet, Brown readily admits that, given current fishing practices, the “ramifications for such animal welfare legislation…is perhaps too daunting to consider.” Billions of humans depend on fish for sustenance, but there is no way to catch a fish without being cruel.

My own dietary decisions are harder to defend. I don't fish, but I love to eat them. Wild salmon is my favorite. Brown’s paper reminded me of a wonderful Stanley Kunitz poem, “King of the River.” The poem describes the heroic journey of a Pacific salmon, as it returns to the fresh water of its birth to spawn and die. If Brown makes the empirical case for fish – they know more than we think, they feel more than we want them to - then Kunitz takes us inside the strange mind of the orange fleshed vertebrate, swimming madly upriver, its suicidal trip driven by a familiar mixture of “nostalgia and desire.”

"A dry fire eats at you.

Fat drips from your bones.

The flutes of your gills discolor.

You have become a ship for parasites.

The great clock of your life

is slowing down,

and the small clocks run wild.

For this you were born."

Brown, C. "Fish intelligence, sentience and ethics. Animal Cognition. June 2014.