Fish have feelings too: Expert claims creatures experience pain in the same way humans do – and should be treated better
- A scientist claims that fish have the same intelligence as other vertebrates
- Fish have good memories, build complicated structures and show behaviour seen in primates – as well as feeling pain like us, he said
- Expert claims fish welfare and fishing techniques should be reconsidered
- It is the latest claims in a debate surrounding how fish respond to stimulus
Fishing may not seem like such a relaxing sport anymore, as scientists claim to have found that fish feel pain, just like humans. One researcher believes fish have the same intelligence as other animals and vertebrates and consequently, people should care more for their welfare.
Flying in the face of what is considered popular opinion, he added fish have good memories and exhibit behaviour seen in primates, such as building complicated structures like specially-shaped sandcastles, as well as using tools.
DEBATE: CAN FISH FEEL PAIN?
In 2003, scientists from Edinburgh claimed to have found the first conclusive evidence of pain perception in fish. They discovered 58 receptors in the heads of rainbow trout responded to electric and chemical shocks.
When the scientists injected bee venom into the lips of some fish, they found they demonstrated a rocking motion – similar to that seen in mammals. ‘The trout injected with the acid that were also observed to rub their lips onto the gravel in their tank… these do not appear to be reflex responses,’ said Dr Lynne Sneddon. She added the study fulfils the criteria for animal pain.
But plenty of scientists disagree and argue that just because fish respond to a stimulus, they do not necessarily compute it as pain. Some argue that fish simply do not have the neuro-physiological capacity to be aware of pain, and that their reactions are measured according to human criteria. Last year, scientists from Wisconsin said fish do not have a brain system or enough sensory nerve receptors to experience suffering. While fish may struggle to get free, the scientists say this doesn’t mean they are in pain. Instead, they show ‘little effect’ from injuries and toxins that would leave humans in agony.
Associate Professor Culum Brown of Macquarie University in Australia, said fish have very good memories, live in complex social communities where they keep track of individuals and can learn from one another. They develop cultural traditions and can even recognise themselves and others. They also show signs of Machiavellian intelligence, such as cooperation and reconciliation, according to the study, which focuses on bony fish and is published in Springer’s journal Animal Cognition.
Professor Brown said the primary senses of the fish are ‘just as good’ and in some cases better than that of humans. The level of mental complexity that fish display is on a par with most other vertebrates, while there is mounting evidence that they can feel pain in a manner similar to humans. While the brains of fish differ from other vertebrates, fish have many comparable structures that perform similar functions.
Professor Brown believes that if some comparable animals are sentient, fish must be considered to be so, too, and therefore their welfare needs should be reconsidered. ‘Although scientists cannot provide a definitive answer on the level of consciousness for any non-human vertebrate, the extensive evidence of fish behavioural and cognitive sophistication and pain perception suggests that best practice would be to lend fish the same level of protection as any other vertebrate,’ he said.
The level of mental complexity that fish display is on a par with most other vertebrates, while there is mounting evidence that they can feel pain in a manner similar to humans.
An expert said that fish (pictured) have very good memories, live in complex social communities where they keep track of individuals and can learn from one another. They develop cultural traditions and can even recognize themselves and others. ‘We should therefore include fish in our ‘moral circle’ and afford them the protection they deserve.’
While the implications of the research could have a big impact on the fishing industry, fish are also used in a similar way to mice in scientific research, so lab conditions would have to be reviewed too. Professor Brown thinks there is little public concern about the creatures’ wellbeing as many people only think of the animals as pets or food, and do not give them credit for being conscious and intelligent.
Another recent study has found that crayfish feel stress in the same way that humans do and can be similarly calmed down using drugs. This is the first time that clear signs of anxiety – normally associated with more complex forms of life – has been observed in a spineless species.
Researchers built a specially-constructed maze to put the lobster-like creatures under pressure and found that their levels of brain chemical serotonin rose. Injecting crayfish with the neurotransmitter was enough to make them anxious, but they could be calmed down with another drug called Chlordiazepoxide (CDZ) which is also used to treat humans. Dr Daniel Cattaert, from the University of Bordeaux said: ‘[Our results] emphasise the ability of an invertebrate to exhibit a state that is similar to a mammalian emotion.’
EVEN MUD CRABS ARE PRETTY SMART
Scientists from Northeastern University in Boston, Massachusetts, discovered that sound – as well as visual and chemical cues that fish give off as they swim along – can cause prey such as mud crabs and shrimp-like crustaceans called amphipods to go into hiding. Professor Randall Hughes explained that fish make a lot of noise to relay distress, find prey, defend their nests and attract mates.
‘We showed that these crabs change their behaviour in response to acoustic signals. They’re just as strong as chemical cues,’ she said. In one experiment, her team piped sounds of predatory fish into a tank of mud crabs and found that they changed their behaviour and did not feed as much.
To work out if the crabs really were hearing the noises, they implanted electrodes into the ‘statocyst’ at the base of the mud crabs’ antennae – a tiny sac containing a mineral mass and thousands of sensory hairs. The electrode signals showed a strong correlation with particle acceleration when the crabs were stimulated with fast pulses of noise, according to the study, which was published in the journal Proceedings of the Royal Society B.
The creatures hear through the billions of displaced particles knocking against the tiny hairs inside their statocysts. The study is the first to show that marine crabs are able to hear and the team will now explore whether the crabs learn to react to local threats.
Animal agriculture, including fishing, is the #1 contributor to environmental pollution, ocean dead zones and habitat destruction. At the end of the day, the best thing we can do to reduce suffering of sentient beings is and environmental damage is to adopt a vegan diet. By eating fruits, vegetables and foods that grow from the earth, we can stop disrupting delicate ecosystems and harming sentient beings that do indeed feel pain the way we do.