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What are the ethics when it comes to the treatment of crustaceans, octopuses and fish? And how do you manage the complex set of animal welfare laws across different states in Australia?

10 Sep 2021 12:22 PM | Giuliana Barajas (Administrator)

Whether they are protected under State and Territory animal welfare legislation depends upon the definition of ‘animal’ in each jurisdiction.
A new bill is being introduced to the United Kingdom parliament to increase protection for fish and invertebrates which raises important ethical questions and whether there should be legislative change in Australia.  The main reason for excluding crustaceans, octopuses and fish is on the basis that they don’t feel pain.  What does science tell us, and how will that knowledge affect welfare laws?

-Katherine Hawes-Legal Consultant - Digital Age

Do crabs, octopuses and fish feel pain? Should they have greater rights to humane treatment?

In the verses of Nirvana's haunting track Something in the Way, Kurt Cobain offers the unremarkable cliche "it's OK to eat fish, cos they don't have any feelings".

It was probably meant as a metaphor, for what we'll never know, but is it actually true? And if not, how has the belief become so widespread?

In the lottery of life, non-mammalian sea creatures in general get a pretty bum deal.

For whatever reason, the empathy we extend to dogs and cats — most mammals, really — doesn't seem to penetrate below the ocean surface.

But could that be, legally at least, about to change?

The United Kingdom parliament is currently debating a bill that would establish an "animal sentience" committee, which would increase welfare protections for fish and invertebrates.

"I have been shocked by some of the treatment of animals such as lobsters, crabs, and squid in the way they have been stored and very often killed,"  Baroness Fookes (Conservative) told the House while debating the bill.

"I believe very strongly that there is already sufficient evidence to indicate that non-vertebrates should be included in the bill."

In Australia, animal welfare laws vary from state to state, and whether an organism is covered generally depends on whether it is classified as an animal.

In South Australia and Western Australia, fish and crustaceans are excluded from animal welfare legislation. Queensland and Tasmania also exclude crustaceans from the definition of an animal.

Exemptions are also made in some states and territories for commercial and recreational fishing.

So do Baroness Fookes and her colleagues have a point — and should we be following suit here in Australia?

Here's what the science says about fish, crustaceans, cephalopods and their experience of pain and other feelings.

Removing fish brains bit by bit

First, it's worth pointing out that this debate isn't settled.

The conflict has largely centred around whether a fish's distressed reaction to something like a hook in its mouth is a pain response or something involuntary that we might compare to a reflex.

A commonly used example to demonstrate the difference between these two reactions is the case of burning your hand on a hot stove.

The immediate response is to pull your hand away. This is a reflex that happens thanks to the transmission of signals between the burnt limb and your spine, which takes place before you experience pain.

Pain occurs separately, after you have pulled the hand away, once the signals are processed in our brain's neocortex via a complex signal pathway.

In the absence of that second process, we wouldn't experience pain, despite having withdrawn our hand from the threat.

Researchers have removed parts of fish brains to see how their response to negative stimuli changes.(ABC: Jo Prendergast)

Fish don't possess a neocortex, nor do they possess any other apparatus that may allow similar processes to take place, according to Brian Key, a professor of biomedical science at the University of Queensland.

He said experiments have been done where numerous parts of a fish brain were removed, and they still respond to stimuli in the same "reflexive" way — much like you pulling your hand away from the hot stove.

"It's what's called autonomous response. We can take a bit out of [the brain] and another bit out and another bit out of the animal and you poke it and it behaves [the same]."

He said it's difficult for people to believe that fish don't feel pain, because we associate those reactions with our own experience.

"Everyone has a set of core values but mostly it runs on 'if you poke it and it reacts, therefore it must feel,'" Professor Key said.

"It's nothing to do with intelligence. It's about whether they have the hardware to feel and I’m saying, no they don’t."

But fish respond to painkillers

On the other side of the coin, there are those who argue that pain is necessary for survival and that, by extension, survival is proof of pain.

A negative or painful experience, according to the argument, is needed to permanently alter an animal's future behaviour towards the source of a threat.

Without that behaviour-altering experience, an animal would continue to put themselves in harm's way, and inevitably suffer life-threatening injury.

Nociceptors which are sensory neurons found in humans, have also been found in fish.(Getty Images: Universal Images Group)

Nociceptors which are sensory neurons found in humans, have also been found in fish.(Getty Images: Universal Images Group)

Numerous studies have shown fish will rapidly change their behaviour following exposure to what we would regard as a painful experience.

And anecdotally, anglers have reported needing to alter their fishing methods — using finer line and well-disguised hooks — in heavily fished areas.

There is physiological evidence to support this view as well.

Nociceptors are sensory neurones found in human skin that help transmit long-ranging electrical signals to the brain.

Their discovery, initially in rainbow trout, is part of the evidence that has effectively "put to bed" the argument against fish feeling pain, according to fish behavioural ecologist Culum Brown of Macquarie University.

"We've known since 2002 that fish have nociceptors, which are the nerves responsible for detecting painful stimuli in humans,"

Professor Brown

Giving fish analgesics that work on humans has also been shown to alter their "pain" and fear response.

"Anxiety is pretty well established amongst a whole bunch of animals, including fishes," Professor Brown said.

"We know from looking at the various drugs we use on humans to prevent anxiety – all those drugs work on fish."

What about crabs, octopuses and other invertebrates?

The nervous systems of octopus evolved independently of humans, yet some of our drugs work on them.(Supplied: Nicole Carrigan)

"Things like cuttlefish and octopus, their nervous systems evolved completely independently of vertebrates. They're basically snails," he said.

"Amazingly, though, some of our [pain-killing] drugs still work on cephalopods."

A 2018 study also found that octopuses given the party drug ecstasy were increasingly sociable, measured through the amount of touch and interaction between one another.

Although nociceptors haven't been found in crustaceans — crabs, prawns, crayfish and the like — there are other clues that point to long-term behavioural changes associated with negative experiences.

Crustaceans avoid objects that administered an electric shock in lab scenarios, and shocked crayfish were found to have higher brain-serotonin concentrations and blood glucose, which researchers put down to a stress response.

An anti-anxiety drug was also found to reduce "fearfulness" in lobsters in a 2014 study.

"When we're talking about sentience we're literally talking about the capacity to feel," Professor Brown said.

"It seems to be an emergent property from complex nervous systems – if you have lots of sensory input from touch and smell and those sorts of things, and they're all being processed centrally, sentience is a feedback."

But Professor Key said similar experiments have been conducted in invertebrates as fish, where parts of the brain and nervous system were removed without changing the "autonomous response" to stimuli.

"Molluscs — same result," he said.

"Part of the family of molluscs are octopuses. They don’t have that hardware. But people would say they're intelligent creatures.

"These animals are complex structures but they just aren’t as complex as humans."

So where does that leave us on the question of sentience and whether animal cruelty laws should apply to fish and crustaceans?

Professors Brown and Key conduct the scientific research that may help ethicists with these questions, but do not profess to be ethicists themselves.

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Professor Brown thinks it's likely that laws regarding the humane treatment of animals will expand as the science progresses.

"The real question at the moment is how far back in evolution does this go — what animals might be sentient and what might the minimum requirements be?

"My guess is after crustaceans, it might be ants and wasps and bees."

But Professor Key said there was now enough scientific evidence on the matter of whether or not pain is a universal trait, that we needed to be discerning about enshrining the rights of animals into law.

"[It] is not [always] justified and would lead eventually to bestowing any animal with a nervous system as being sentient."


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