Are fish conscious?

[Ulrikke]

What's your opinion? Here is the latest:

"British scientists say that after years of debate, they now have proof that fish feel pain"

Animal activists are on the warpath after a study released on April 30 showed how rainbow trout react to discomfort. They condemned fishing as cruel and demanded an end to the sport — but anglers themselves dismissed the study.

The research found that fish have receptors in their heads and that subjecting them to noxious substances causes “adverse behavioral and physiological changes.”
“This fulfils the criteria for animal pain,” said Dr. Lynne Sneddon, who headed the research, published Wednesday by the Royal Society, Britain’s national academy of science.

Bee venom or acetic acid was injected into the lips of some of the trout, while control groups of fish were injected with saline solution or merely handled.
The trout injected with venom or acid began to show “rocking” motion — similar to that seen in stressed higher vertebrates — and those injected with acetic acid began rubbing their lips in the gravel of their tank.

“These do not appear to be reflex responses,” Sneddon said.

The affected fish also took three times longer to resume feeding activity, compared with those in the control groups.

The team from the Roslin Institute and the University of Edinburgh found the fish had polymodal nociceptors — receptors that respond to tissue-damaging stimuli — on their heads.

It is the first time these receptors have been found in fish. They have similar properties to those found in amphibians, birds and mammals including humans.

Animal activists said the findings showed that fishing was cruel.

“We would encourage anglers to lay down their rods. It’s ridiculous that in 2003 we are still talking about whether fish feel pain — of course they do,” Dawn Carr of the People for the Ethical Treatment of Animals told Sky News.

But anglers vowed to keep on enjoying their sport.

Dr Bruno Broughton, a fish biologist and NAA adviser, said: "I doubt that it will come as much of a shock to anglers to learn that fish have an elaborate system of sensory cells around their mouths... However, it is an entirely different matter to draw conclusions about the ability of fish to feel pain, a psychological experience for which they literally do not have the brains," he said."

He quoted from a study by Professor James Rose of the University of Wyoming, US, in which it was found fish did not possess the necessary and specific regions of the brain, the neocortex. "Fish just don't have the brains to recognise pain"

“Until we have proper, bona fide evidence, we will never know. It’s supposition,” said Charles Jardine, director of pro-angling group Gone Fishing. “I don’t think the millions of anglers throughout the whole of the world would see themselves as cruel individuals.”

[ANDY-J2]

I've been involved in fishing for over twenty years and I don't believe that most species of fish feel pain.When a fish is released into the water it usually swims away without showing much signs of distress and it is not unknown for a released fish to be caught again shortly afterwards,so evidently the experience of being caught doesn't traumatise them too much.The one exception to this however is eels and I am certain that they are capable of feeling pain.When they are out of the water they will attempt to bite you and also they release large amounts of mucous from their skin which is a defensive response and shows that they are feeling distress.

[Ulrikke]

I wonder if there are any studies on eels, Andy.

On the rainbow trout study, they investigated the fish for the presence of nociceptors, sites that respond to tissue-damaging stimuli. And found 58 receptors located on the face and head of the trout that responded to at least one of the stimuli. "Of these, 22 could be classified as nociceptors in that they responded to mechanical pressure and were stimulated when heated above 40 Celsius. Eighteen receptors also responded to chemical stimulation and can be defined as polymodal nociceptors."

"These polymodal receptors are the first to be found in fish, and resemble those in amphibians, birds and mammals, including humans. But mechanical thresholds were lower than those found in human skin, for example, perhaps because fish skin is relatively easily damaged."

"The mere presence of nociception in an animal is not enough to prove that it feels pain, because its reaction may be a reflex. Proof requires demonstrating that the animal's behaviour is adversely affected by a potentially painful experience, and that these behavioural changes are not simple reflex responses."

These fish do not have the neuro system required to recognize pain. They have – as the study suggests – what could be classified as nociceptors: the response to damaging stimuli. But a reaction to stimuli would not be the same as experiencing pain, I don't think, since this would require a consciousness infrastructure that fish do not possess.

However, I do think that fish are 'conscious' in other ways.

[BatEl]

The way Mankind has and is treating the World, the question should be put to Mankind! r we Conscious???????????????????Most of of seemingly NOT!

[-Sigurd-]

If it turns out that fish lack the brain structures required for pain to be experienced, then the argument is finally settled.

I think there are good reasons for doubting that they feel pain. If pain is there primarily to produce changes in the behaviour of the individual towards harmful situations and features of the environment, it has to be able to make use of a well developed memory system, something that fish are not reputed to have. In fact fish are well known for lacking any kind of long term memory. So, hard to believe as it may be for some, it seems that fish brains may indeed be unable to support the kind of relatively high level experience that pain represents.

I don't think that eels are likely to be sufficiently more evolved than other species of fish; I suspect that their thrashing around etc is really just responsive behaviour too. What we would need to see (apart from evidence that they have the relevant brain structures) is learned aversive behaviour from damaging encounters.

[ANDY-J2]

The eel does have a higher level of intelligence than most other fish.It is a voracious predator which relies on stealth and guile to catch its prey.Whereas most fish will simply take a bite at any available bait the eel will lift the bait and carry it for some distance before devouring it and if it feels any pressure on the fishing line it will immediately drop the bait so it therefore must have some awareness of danger.Also they can survive out of water for several hours and it is not unknown to find eels on dry land some distance from any source of water so they are capable of more complex patterns of behaviour than other species.Unlike other fish,when caught an eel will react by attempting to bite you and I've often removed eels from a keep net to find them with their jaws firmly clamped on another fish so they are capable of perceiving that they are under threat and react aggressively.Having caught many eels I would have to say that they do appear to have some degree of intelligence and they do seem to be able to experience distress if not actual pain.

[Ulrikke]

Andy, I found some interesting info on Eels but no studies that indicate they are more 'evolved' than other fishes – although, of course I am taking your experience with them as information – if you have any additional data, let us know.

Eel facts:

A fish full of paradoxes and unsolved questions.

The eel's natural history has fascinated and mystified thoughtful observers from Aristotle to Freud, and despite more than a millennium of study, little is known for sure about it.

Eels are able to live up to 36 hours out of water, and they can cross land to reach water, which explains their presence in landlocked ponds and lakes.

The eels found in North American rivers, lakes, and ponds belong to the species Anguilla rostrata, and those in European fresh waters are Anguilla anguilla, but the two are virtually identical, differentiated by only a few small anatomical details.
Both are serpentine, muddy brown fish that can grow up to a yard long. Both species have a robustly flavored flesh, as well as one of the most unusual life cycles of any animal in the world.

They are believed to hatch in the Sargasso Sea, a deep, two-million-square-mile sea in the Atlantic Ocean, between the Azores and Bermuda, bordered by strong currents. The eel larvae, shaped like tiny leaves, drift on a journey that can take years, toward either Europe or North America. Finally, for reasons still unknown, they will choose to enter a river where they take on an eel’s form and head upstream to reside for up to a score of years as adults, before returning downriver to salt water. When they reach the coast, they jettison their digestive systems and swim for months without eating, until they reach the Sargasso. There, they mate and die.

Scientists are convinced that the theory of Sargasso Sea reproduction is correct, because the larvae captured there are so small that they must have hatched nearby. But a live adult eel has never been captured in the Sargasso.