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Fish: think or swim?

Published in The Vegetarian magazine - Spring 2017




As vegetarians, we know fish are animals and therefore are very much off the menu for  anyone following a veggie diet. But how much do we really know about these wonderful  aquatic creatures? One person who certainly knows plenty about fish is the ethologist,  author and speaker at the Vegetarian Society's KIN event back in 2015, Jonathan Balcombe.  Here we take a look at some of the topics discussed in his book: What a Fish Knows.

The sheer expanse of ocean covering the Earth’s surface and the unimaginable multitude of fish that live beneath the waves are truly awe-inspiring. The number of species of fish  on our planet outnumbers all known species of mammals, birds, reptiles and amphibians put together. The mass migration of salmon and eels over thousands of miles from sea to  freshwater is astonishing, as is the sheer size of herring 'mega-shoals' comprising hundreds of millions of fish and can be seen from the air, covering dozens of square kilometres.

From afar fish in their masses appear to be an undifferentiated shoal living virtually  automated lives. But could the truth be that, far from being anonymous members of the shoal, all fishes are in fact individuals? Jonathan Balcombe, author of a new book, What
A Fish Knows, thinks this is the case.

Jonathan Balcombe is an ethologist – someone who studies how animals have adapted to their surroundings and looks in intimate detail at their behaviour, their capacity for learning, their interactions with other individuals or even other species of animal. He  believes the scientific understanding of fish has now advanced to a point where it may be time for a paradigm shift in how we think about and treat fishes.

It is, Jonathan maintains, when one combines observation of individual fish with broader understanding of behaviour that the true story begins to unfold.

It is often said that fish are 'primitive'. Certainly, in evolutionary terms they have been around a long time and much longer than birds or mammals, but says Jonathan, this means they have had a lot of time to develop in some surprisingly sophisticated ways.

Despite their glassy-eyed appearance, fishes have evolved visual capacities beyond those  of human beings. Whereas we have three types of colour sensitive structures called 'cones' in our eyes, most fishes have four and are ‘tetra-chromatic’ allowing them to see a wider range of colours more vividly than we do – and in some cases to even see near ultraviolet (UV) which is invisible to us.

Brain and Sentience

"One of the things that has always been used against fish in our brainsize obsessed scientific culture," says Jonathan, "is the notion that fish have such small brains relative to their body size." But Jonathan goes on to point out "this actually overlooks one significant factor in the evolution of marine creatures: the buoyant effect of water. In water there is no premium on limiting body size relative to brain size. Hence the largest animals – whales (albeit mammals not fishes) live in the sea not on land. Like whales, fishes also benefit from living in a practically weightless environment where having large, powerful muscles to propel them is a great advantage."

Therefore science, he thinks, has unfairly underestimated the brains and possible inner lives of fishes by misjudging the significance of their brain-body size ratio.

But does a fish’s brain enable a fish to be conscious? Science in general has long resisted the possibility that consciousness could be present in animals. It is, of course, a uniquely difficult subject to study on account of it being a fundamentally private phenomenon.

Jonathan says there are some very good reasons to expect that fish are conscious. As vertebrates they have the same basic body plan as other animals, such as mammals, including a backbone, a suite of senses, and a peripheral nervous system governed by a

But not all scientists agree that fish are likely to have the capacity for consciousness and in particular to feel pain. In fact some scientists claim that fish are entirely unaware of anything: unable to think, feel or even see.

The argument among scientists stems from the fact there are key differences between the brains of mammals and those of fishes.

They claim that in order to possess the capacity for pain one must possess a neocortex: a structure in the brain which is unique to mammals. However Jonathan believes that the crucial role of the neocortex has been disproved by parallel studies of birds. Birds lack a neocortex but have a high capacity for learning, memory and social interactions. Consciousness in birds is virtually universally accepted and more importantly is believed to be rooted in an alternative brain structure called the paleocortex. The fishes’ equivalent brain structure to the paleocortex is the very diverse and complex pallium.

Fishes are certainly awake but are they aware? Being aware involves having experiences, taking notice, remembering things. And according to Jonathan, an aware creature is not merely alive: it has a life.


So what of fishes’ ability to learn? One study of the frilfin goby, a small North American rock pool fish, discovered that while swimming over rock pools at high tide, the fish memorises the relative positions of the rock pools in its feeding zone so that at
low tide it can feed by making strategic jumps from pool to pool without landing out of water on the rocks.

Another study looked at whether fishes could be fooled by the kinds of optical illusions that we humans can enjoy. In a study of redtail splitfins – a species of fish from highland Mexican streams – fish learned to tap the larger of two discs to get a food
reward. Once they had mastered the task, the scientists presented the fish with the Ebbinghaus illusion (see image below) which consists of two discs of the same size, one of which (on the left in the illustration) is surrounded by larger discs, making it appear smaller (at least to human eyes) than the other disc on the right, which is surrounded by smaller discs. In the study, the splitfins preferred the disc on the right – the disc that appears to be larger. This result showed the scientists that redtail splitfins do not perceive things in a mindless, stimulus-response way. Rather they form mental concepts – sometimes fallible ones – based on their perceptions.


Tool use

Until recently the use of ‘tools’ – the ability to manipulate an object to perform a task – was believed to be a phenomenon unique to animals such as chimpanzees and crows. However, in recent years a species of wrasse called an orange-dotted tuskfish has been
filmed feeding in a quite specialised way. The tuskfish seeks out a clam, uncovers itusing jets of water expelled from its gills and then carries it in its mouth some distance to a favourite rock where it cracks the clam open using several rapid head-
flicks, thus making an inaccessible morsel ready for eating.

Social recognition

Some social behaviours of fish are remarkably sophisticated too. Studies reveal that fish not only recognise and navigate their territory but that they can recognise each other too.

It has long been established that paired species of bird such as albatross and penguin recognise each other after long periods apart and that some highly territorial warblers will only tolerate birds they recognise as locals. But this kind of ability to recognise familiars has also been observed in fish. Studies of the Pacific damselfish have revealed that the three-spot damselfish can recognise his neighbour. In an ingenuous test a researcher chose a dominant territorial male on the Panama reef and captured some other male damselfish occupying nearby territories – some were immediate neighbours and some were from territories fifty feet or more away. The researcher put the males in transparent containers and then placed the containers inside the territory of the dominant male who remained free-swimming. The results were striking. In 15 separate tests, when presented with the stranger, the dominant male would vigorously attack, ramming the container and attempting to bite. However, when presented with his neighbour, in a similar container, he virtually ignored him.

Jonathan’s book is jam-packed with example after example like this of the fascinating evidence of fishes’ extraordinary inner lives but having studied so many different animals throughout his career, how did he first come to be so interested in fish?

Like many people who grow up to become zoologists, biologists or otherwise involved with animal studies Jonathan felt a deep connection to animals from an early age, observing every creature that his backyard had to offer. But, says Jonathan, when it came to fish, like most people he didn’t immediately feel a connection or necessarily see them in the same light as other animals.

Like many an eight year old, Jonathan experienced a small boat fishing trip. For him it was on the shimmering water of Sturgeon Bay, Toronto, near where he grew up.

"I have some fond memories of that experience," he says, "but as a sensitive boy with a soft spot for animals, I was disturbed by a lot of what went on in that rowing boat. I worried about the worms and the pain the hooked fish might feel, but, as my kindly summer camp leader didn’t seem to think there was anything wrong about our fishing trip, I rationalised that it must be ok."

Another formative experience involved a mishap at school when moving a goldfish and its bowl from one classroom to another. As Jonathan explains: "Dropping that bowl and the ensuing frantic search for the stranded goldfish was a nightmarish experience and one that made a deep impression on me."

But he says it wasn’t until he was in his final year of his undergraduate degree and taking an ichthyology (fish studies) course that he seriously began to question whether we ought not to consider fish as we do other animals.

And Jonathan is clear that personal experience matters. In What A Fish Knows he draws together the findings of scientific studies alongside the personal testimonies of deep sea divers, aquarium enthusiasts and other people who have made their own observations of fishes at close quarters.

what a fish knows book"My book aims to give voice to fish in a way that hasn’t been possible in the past. In researching this book I have sought to sprinkle the science with stories of people’s encounters with fishes. Anecdotes carry little credibility with scientists, but they provide insight into what animals may be capable of that science has yet to explore, and they can inspire deeper reflection on the human-animal relationship. What this book puts forward is a simple possibility with a profound implication: that fishes are individual beings whose lives have intrinsic value – that is value to themselves. This I believe should qualify them for inclusion in our circle of moral concern."

Jonathan is the director of animal sentience at the Humane Society Institute for Science and Policy and the author of four books including Second Nature, and Pleasurable Kingdom. He was also a speaker at the Vegetarian Society's event KIN in 2015.

Content reproduced from What A Fish Knows by kind permission of Oneworld Publications.


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