The fish on the counter often arrives already clean, tidy, silent even in the form in which it is sold. Fillets, slices, trays, crushed ice, price tags per kilo. All very practical, all quite far from the animal that a few steps before was breathing underwater, reacting to stimuli, looking for oxygen, going through fear and stress. Precisely this distance makes the suffering of fish one of the most convenient parts to ignore in the food chain: it happens out of sight, in a short time compared to the life of the animal, within practices that for years have been considered normal because the fish simply doesn’t scream.
A study published in Scientific Reports he tried to remove that gray area from the field of impressions and measure it with a very concrete unit: minutes. The work focuses on rainbow trout, a species bred and consumed in many parts of the world, and analyzes a practice still widespread in fishing and aquaculture: air asphyxiation, that is, the agony of the animal being pulled out of the water and left to die without effective preventive stunning. It is estimated that a trout can withstand about 10 minutes of moderate to extreme pain on average, with a credible range of 1.9 to 21.7 minutes; compared to weight, the figure becomes approximately 24 minutes of pain per kilo of fish.
When the fish leaves the water, the body continues to react
The hardest detail lies in the slowness. When a trout is taken out of the water, its organism does not turn off like a switch. The gills, designed to function submerged, collapse. Available oxygen collapses, carbon dioxide increases, the blood changes balance, the muscles become fatigued, the brain proceeds towards loss of consciousness through a sequence that can last several minutes. In the meantime the animal moves, gasps, tries to react. The study analyzed behavioral, neurophysiological and pharmacological indicators to estimate the intensity and duration of the negative experience, using the Welfare Footprint Framework, a method that translates animal well-being into time spent in different affective states.
This setting changes the way you look at the problem. Until now, animal suffering was often described with generic words: stress, discomfort, pain, mistreatment. Useful terms, of course, but difficult to compare when deciding where to intervene, with what costs and with what urgency. The Welfare Footprint Framework tries to do a job similar to what already happens in other areas, from environmental footprints to public health indicators: it brings a complex phenomenon into a common, legible, comparable scale. In the case of rainbow trout, the scale is ruthless in its simplicity. Each animal can remain conscious and suffering for minutes which, within an industrial system, multiplied by millions or billions of individuals becomes an enormous mass of invisible pain.
The authors divide the process into phases, from the first alarm of emergence to the depression of brain activity that precedes unconsciousness. Not all suffering has the same intensity, and for this reason the model distinguishes different levels, from less serious states to pain capable of compromising the animal’s basic functions. The result remains harsh: death from air asphyxiation, often perceived as an almost “natural” consequence of capture, presents itself as a slow, stressful, biologically violent practice.
Ice seems like a cleaner solution, but for the trout it can prolong the agony
In common parlance, placing a fish on ice gives an impression of order. Cool, preserve, slow down. It sounds less brutal than an animal left gasping for air. For rainbow trout, however, the picture is more uncomfortable. Being a species adapted to cold waters, cold alone does not guarantee rapid loss of consciousness. Indeed, exposure to ice or ice slush can slow the metabolism and prolong the time it takes for the animal to lose sensitivity, adding thermal stress, possible tissue damage and fear.
Suffering, then, can begin long before the actual killing. Crowding, transportation, handling, waiting, changes in water and environmental conditions weigh on the fish’s body and can accumulate stress for hours. The study reports precisely this: the slaughter phase is short compared to the life of a farmed fish, which in the case of trout can reach commercial weight after many months, yet it remains a crucial point of intervention because it concerns a huge number of animals and is technically more correctable than other parts of the supply chain.
Here two methods that have already been discussed for years in fish welfare come into play: electrical stunning and percussive stunning. The first, when it really works, can render the animal unconscious before death and significantly reduce the minutes of suffering. Study estimates indicate that a properly applied electrical stun could prevent between 60 and 1,200 minutes of moderate to extreme pain for every dollar invested in the implants. It is a number that explains why this type of intervention is considered very promising in terms of cost-benefit.
The problem lies in that small and decisive word: correctly. Under commercial conditions, electrical stunning can fail due to inadequate voltages, poorly placed electrodes, uncalibrated machinery, hasty procedures, or insufficient controls. Percussive stunning, i.e. hitting the head, can be effective in the laboratory and in well-managed contexts, but it becomes more complicated on a large scale: fish have different sizes, operators get tired, errors leave the animal conscious just when it should already be numb. The guidelines of organizations such as the RSPCA, for Atlantic salmon and rainbow trout, indicate that percussive stunning followed by bleeding and electrical stunning are acceptable from a welfare point of view.
In Europe the topic moves within a framework that is still incomplete. The European regulation on the protection of animals at the time of killing includes farmed fish, but with less specific requirements than other land animals. The European Commission has recognized the particularity of the issue for years, while EFSA has produced specific scientific opinions on stunning and killing methods for various fish species, including rainbow trout. EFSA also recalls that its assessments serve to provide scientific basis for reducing avoidable pain, stress and suffering.
The novelty of the study lies in making the old alibi of vagueness more difficult. Talking about “a few minutes” changes little in public perception. Talking about an average 10 minutes of intense pain, with cases that can exceed 20 minutes, shifts the discussion. Also because enormous numbers of fish are killed every year: the study recalls global estimates of 1,100-2,200 billion wild fish and 78-171 billion farmed fish slaughtered every year. On such a scale, even a small reduction in individual pain becomes gigantic when multiplied by the number of animals involved.
The discussion also concerns consumers, although the consumer often enters when everything is already finished. The labels talk about origin, fishing method, farming, sometimes environmental sustainability. Much more rarely do they tell how the animal was killed. Yet that step is as much a part of the ethical quality of the product as the impact on ecosystems, the density of farming or the use of feed. The Welfare Footprint Framework also offers a more concrete language for certifications, controls, company specifications and public standards: minutes of suffering saved, effectiveness of stunning, training of operators, real verification of unconsciousness.
Of course, rainbow trout don’t solve the problem. Salmon, sea bass, sea bream, tilapia, catfish and many other species have different physiologies, different resistances to oxygen deficiency, different reactions to cold and stress. The study invites us to avoid shortcuts: the general mechanisms of asphyxia, from hypoxia to acidosis to metabolic exhaustion, may present similarities between species, but each animal requires specific data to estimate the duration and intensity of suffering.
It remains a consequence that is simple to absorb and difficult to avoid. Fish are not silent bodies made available to the supply chain. They have biological responses, they experience stress, they react to painful stimuli, they go through states that animal welfare research is learning to describe with ever greater precision. EFSA, in its work on fish welfare, refers to the need to reduce unnecessary pain, stress and suffering.
From here the request for more severe reforms becomes very concrete: effective stunning before killing, checks on equipment, trained staff, reduction of crowding and handling, minimum standards that can also be verified in private certifications. No rhetoric. Only the recognition of a biological fact that industrial convenience has long kept underwater. The fish on the school will continue to be silent. The minutes, now, speak enough.
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