It is likely that installing a shrimp stunner reduces global suffering as much as making the carts in a single Walmart less squeaky for 20 minutes a year. Or perhaps not at all.

Open Philanthropy has handed $2 million to the Shrimp Welfare Project (SWP), primarily to promote electrical stunning devices, and fund staff to push policy changes. Each stunner costs $70,000 to purchase and $50,000 to distribute. The goal? To "reduce suffering" when 500 million shrimp are harvested annually by cutting their death time from 20 minutes in ice slurry to 30 seconds via electrical stunning.

This initiative may sound odd at first glance but the SWP has produced numerous blog posts, elaborate spreadsheets, and lengthy PDFs to justify their approach. They have clearly thought this through extensively, and I will look to provide a short, but equivalently thorough rebuttal.

They claim that the shrimp stunner renders shrimp “unconscious” by synchronously depolarizing their neurons with an electrical current over three seconds and then kills them around 27 seconds later. This replaces the cheaper and more common process of immersing shrimp in an ice slurry which leads to immobilisation in around a minute and death in about 20 minutes.

Promoting this stunner based approach implies that the people behind the SWP believe that disrupting neuronal firing stops suffering, a physicalist perspective that I agree with.

My disagreement, however, is with the methodology, and the assumptions that the SWP depend on to justify their conclusions; namely behavioural tests, and loose biological analogues to justify shrimp consciousness and suffering.

Neuroscience offers several frameworks for understanding consciousness:

First, it should be mentioned that shrimp have ≈100,000 neurons. Humans have ≈86 billion neurons, and only 10% of the human brain is likely to be involved in any sort of conscious calculation. Neuronal firing and interaction alone does not imply the existence of consciousness or awareness.

Global Workspace Theory states that consciousness arises when information is globally broadcast across distributed brain systems humans achieve this via coordinated fronto-parietal networks, as shown in EEG, fMRI, and MEG studies on consciously available stimuli in the human brain, but shrimp lack anything comparable; no cortex, no long range networks, no unified communication hub.

Electric Field Theories emphasize stable macroscopic fields that bind cognition. Humans generate such fields across large, integrated networks, but shrimp nervous systems are small, modular, and discontinuous, making coherent fields that integrate information very unlikely. 

Marker’s midbrain theory of consciousness would imply that all vertebrates are conscious, and create a cohesive evolutionary pathway for consciousness that excludes shrimp. These theories locate consciousness in vertebrate midbrain integration hubs like the superior colliculus and periaqueductal gray. Shrimp have no clearly analogous structure, so they likely lack spatially unified representations. 

Integrated Information Theory gives shrimp their strongest case for awareness: they integrate information locally, yet their overall Φ is likely tiny given sparse neurons and limited connectivity.

Based on these thresholds, P(shrimp consciousness) is very low.

Now let’s discuss P(shrimp suffering).

If we grant shrimp the minuscule amount of awareness that IIT would give them, then we must gauge their ability to suffer. It takes some skill to suffer.

Under most neuroscientific theories, suffering is not just about detecting damaging stimuli, but requires integrating multiple streams of information into a unified evaluative model that links sensation, memory, affect and motivation. The scientific consensus is that suffering evolved as an adaptive feature to motivate avoidance of harm. Some argue that consciousness evolved to create a self-model that tracks current bodily states, stores and retrieves past experiences and projects future scenarios to guide avoidance behaviours.

There is no evidence that shrimp are capable of any of those mechanisms, and despite the SWP’s unsubstantiated claim that shrimp can undergo associative learning (https://www.shrimpwelfareproject.org/are-shrimps-sentient), which most likely comes from research on crabs (not shrimp), I found no such evidence myself.

Shrimp can detect noxious stimuli, and have been observed to groom damaged antennae. There is even evidence of reduced grooming after opioid administration implying the existence of damage detection, which LSE saw as enough evidence to claim sentience. This is clear evidence that shrimp can detect damage to their bodies. That does not mean they suffer.

You, as a human, associate injury with negative valence. That does not mean shrimp do.

Your suffering scales with Anterior Cingulate Cortex (ACC) activation, not with increased activation of pain receptors. Most vertebrates have ACC analogues, but shrimp don’t. Human suffering is largely caused by ACC activation, where electrical stimulation of the region generates a reported sense of “existential distress” and lesions to the ACC allow humans to detect pain without suffering. Shrimp certainly can’t suffer in any way that we can relate to.

You can make the argument that shrimp developed the ability to suffer independently. Under this assumption, consciousness and suffering evolved along the malacostran lineage hundreds of millions of years ago in the Cambrian period, as the shrimp nervous system hasn't changed much since then. This would imply that there are tens to hundreds of quintillions of sufferers inhabiting our earth. The SWP’s long term goal is to slightly reduce the suffering of 0.0004% of them (400 billion farmed shrimp) for around 20 minutes over their lifetimes. This would imply a yearly suffering reduction of 0.00000002% over the malacostran family.

If you still aren't convinced by all these arguments, I will put forward something more analytical, based on neuron counts. The SWP criticises neuron counts alone by mentioning synapse density and topology, neuron size, conduction velocity, refractory period, and inter-neuronal distance. Funnily enough, on all of these markers, shrimp fall orders of magnitude below humans. Their conduction is slow, neurons large and widely spaced and their synapses sparse and simple. The neuron count measurement is the most generous I could reasonably use.

The human brain contains approximately 86 billion neurons, but consciousness researchers theorize that only about 10% actively participate in generating conscious experience. This gives us 8.6 billion conscious neurons per human. Let's call this “one sentium”, the conscious capacity of a single human being.

Applying the same logic to shrimp, with their 100,000 total neurons and assuming the same 10% participation rate, each shrimp contributes 10,000 neurons to conscious processing (not unreasonable based on the architectures of their brains), simple arithmetic tells us that 860,000 shrimp equal one sentium of conscious capacity.

But not all sentiams are created equal. Shrimp lack a bounded sense of self, memory beyond a few seconds, cross-modal sensory integration, and any framework for complex experience. At best, a shrimp sentium would encode only the most surface-level sensory experience: raw sensation without context, meaning, or emotional depth. Think of the mildest irritation you can imagine, like the persistent squeak of a shopping cart wheel at Walmart.

A typical Walmart hosts about 550 shoppers at any given time, all of them pushing those squeaky carts. That's 550 human sentiams experiencing mild irritation. Each electrical stunner processes approximately 500 million shrimp annually, equivalent to 581 sentiams of conscious capacity. The stunner reduces their suffering from ice slurry death, which takes about 20 minutes.

I’ll ask the question, is this worth $100,000? Is this even worth $10? $1? 10¢?

It is likely that installing a shrimp stunner reduces global suffering as much as making the carts in a single Walmart less squeaky for 20 minutes a year. Or perhaps not at all.

The Shrimp Welfare Project wants shrimp to suffer so they can have a new problem to solve. 

While they  invest millions into speculative welfare gains for shrimp, the same effort and resources could fund malaria nets to save children’s lives, deworming programs to save children’s lives, vitamin A supplementation to prevent blindness, disaster relief, tuberculosis and HIV treatment, mental health treatments, maternal health services, lead paint removal, school feeding programs, safe water and sanitation projects and so many more proven efforts that actually reduce suffering.