You might not eat this fish if you knew how smart it is. (Photo: Khaled Desouki/AFP/Getty Images)

Fishing has long been a paradoxical endeavor. In global terms, few foods are more important to human health, but, with 63 percent of fish species overfished, few actions are as detrimental to the environment.

There are obvious qualifications to this claim. Fishing in a pond with a humble pole and dredging the ocean with a beam trawler are radically different variations on the same theme, and hardly warrant comparison in terms of ecological impact. But recent studies suggest that ecology isn’t the only reason to be concerned about fishing. Emerging evidence that fish are unexpectedly intelligent animals with an acute ability to feel pain — and may possess an aquatic consciousness of sorts — places them squarely in the center of an emerging ethic that grants to sentient animals basic welfare consideration. And this realization, it seems, leads to a conundrum: Fish might be too smart to deserve being eaten. Are we in any way prepared to act accordingly?

In terms of documenting basic fish intelligence, researchers have made critical discoveries in recent years. We now know that fish exhibit advanced Pavlovian responses to food offerings, a behavior that highlights “associative learning” rather than simple expressions of instinct. In one study, fish placed in a new environment reliably recalled where and at what time they were fed, memorizing this information after only 14 trials, as opposed to 40 for rats.

Relatedly, fish have demonstrated a navigational ability that outstrips that of human toddlers. When introduced to novel settings, they quickly associated safe regions (stable rock pools) with immobile geographical features (such as a patch of grass). When tides were suddenly manipulated, they sought out those pools, thereby avoiding being beached on a sandbar during an unanticipated disturbance.

Other findings edge us closer to thinking about fish as conscious decision-makers. Younger salmon have been shown to imitate their elders in social situations. When presented with a new food in captivity, for example, they will hesitate before cautiously testing the food. But when they are housed in a tank with older fish, and witness these elders eating the strange food, they follow suit, chomping away with far greater aggression and, it seems, confidence.

Fish have even joined the exclusive club of tool-users — something that we’ve long deemed (mistakenly) an exclusive hallmark of human intelligence. In 2011, a diver caught on camera an archerfish carrying a clam over to a rock and slamming the bivalve until it cracked. After eating the clam, the fish spit out the shells before continuing the hunt. It’s difficult to watch a video such as this one — it’s a tenacious wrasse on a mission — and not posit a substantial degree of intent. Whether you want to call it “consciousness” or not, it’s more than mere instinct.

In perhaps the most striking finding, an Oxford University study, released this year, determined that fish were able to recognize human faces. The ability to do this has long been linked with advanced brain development — specifically the presence of a neo-cortex. But fish, which lack a neo-cortex, were able to identify the one person who had fed them from a line-up of 44 other people. They did this with 80 percent accuracy. Upon hearing the results, Australian fish biologist Culum Brown said, “the neo-cortex is not the grail of intelligence.”

Nor are scientists convinced that advanced brain development is required to feel pain. Certainly the issue is disputed, with many arguing that fish lack the cognitive wherewithal to experience pain in the same general way humans do. But others note that a trout head contains 58 pain receptors and that, when injected with venom, fish will rock back and forth they way mammals experiencing pain do. In another case, fish whose mouths were dosed with acid jammed their faces into gravel and rubbed them.

Reflecting on these findings, scientists and animal behaviorists have weighed in on the possible ethical implications. Perhaps most vocal has been Brown, the Australian researcher. He writes: “Although scientists cannot provide a definitive answer on the level of consciousness for any non-human vertebrate, the extensive evidence of fish behavioral and cognitive sophistication and pain perception suggests that best practice would be to lend fish the same level of protection as any other vertebrate.”

In a Vox interview, Brown observed that it was relatively easy to find beef or lamb that was raised under humane circumstances, but noted that such a standard “does not exist for fish. There’s no such thing.” He also thought it “bizarre” how there were “lots of people who call themselves vegetarians, but they eat fish. As though fish aren’t animals. Are they potatoes? I don’t really understand that perspective.”

What’s easier to imagine, though, is a type of pragmatic compassion for sentient animals that asks us to direct our noble reformist energies to where they can be realistically directed.

The biologist and ecologist Marc Bekoff, who has spent his career studying animal behavior (while working closely with Jane Goodall), said this in light of what we are learning about fish intelligence: “It’s high time that use what we know on behalf of fish and other animals who are used and abused in the countless billions. Fish clearly are not things nor disposable objects, but rather sentient and feeling beings.”

It is estimated that as many as 2.7 trillion fish are caught globally every year. And that number brings us straight to the conundrum. There is, on the surface, an easy logic to follow when it comes to the implications of fish sentience: Fish appear to be sentient, they seem to feel pain and demonstrate a consciousness, many ethicists and biologists argue that we therefore need to consider their welfare, and, because we care about animal welfare, and because we like to follow the science, we concede that, indeed, we must take into consideration fish welfare.

But how?

It’s difficult to imagine how anyone could hook fish from the oceans, or haul them on deck in a net and suffocate them, in a welfare-oriented way. It’s more difficult to imagine establishing a welfare-oriented fish farm. And it’s yet even more difficult to imagine a world in which we give up eating fish. Nor, given how many impoverished global citizens need fish as a basic source of nutrition, should we necessarily want that.

What’s easier to imagine, though, is a type of pragmatic compassion for sentient animals that asks us to direct our noble reformist energies to where they can be most realistically directed — land-based farm animals — and seek meaningful welfare reforms within that circumscribed realm (one in which welfare activists have, in global terms, made barely a dent).

To include fish in our quest for a more comprehensive animal welfare reform effort is, of course, consistent with the principles underlying the quest to treat sentient animals with moral consideration. It’s also consistent with our efforts to improve the food system. But it’s inconsistent with the reality currently under our nose. To assume the burden of improving the lives of 2.7 trillion animals — on top of the billions that are already at the center of welfare reform programs — could easily make the welfare imperative seem untenable, if not absurd.

There is no need to ignore the science on fish intelligence. It’s fascinating stuff. But we must be realistic about how we can act on it.