Challenging Fish Sentience Denial With Science

Recent empirical studies have provided evidence of fish, cephalopod, and crustacean capacity for nociception and pain, suggesting that their welfare should be taken into consideration. Some skeptics, rejecting the precautionary principle, however, have denied that any study actually proves pain or other aspects of sentience in fishes. In this study, a group of researchers working in the fields of fish behavioral science, animal sentience, welfare, and conservation gathered together to address scientific shortcomings present in fish sentience denial recently voiced by other colleagues.

Several of the study’s authors note that previous research argues that fishes meet criteria for sentience, including the ability to experience positive and negative emotions. Meanwhile, awareness, an inherent quality of sentient beings, is often challenging to demonstrate in non-human animals. However, many studies of behavior and cognition have successfully reported evidence of perceptual, cognitive and higher-order awareness in fishes. Some examples include:

• Kin recognition in early fish larvae
• Fishes’ ability to distinguish their own odours from that of others
• Self-directed behaviours in mirror self-recognition tests – an ability considered indicative of awareness when mammals and other groups of animals are studied
• Sophisticated learning abilities, in some cases surpassing those of chimpanzees, orangutans and capuchin monkeys

The question of pain – seen as one of the key aspects of sentience – is all but settled, as several studies have shown unique molecular, electrophysiological and in vivo changes in fishes’ forebrain and midbrain regions during painful stimulation. However, clear differences between mammalian and fish brains prevent us from expecting that the sensation of pain is processed in the same way.

The complexity, though, is there. Goldfish, for instance, were shown to learn to avoid an area where they had received an electric shock previously, exhibiting long-term avoidance at a cost – even when food is provided only in the said area. Another study showed that five days after fertilisation, larval zebrafishes already respond to noxious, potentially painful stimulation in the same way adult fishes do, indicating that studies which still use live fishes can uphold the 3Rs principles and reduce the overall time they are kept in captivity.

So how come fishes’ welfare is still frowned upon? Just the mere fact that the fishing industry count them in tonnes caught instead of individuals indicates that their potential for suffering is immense, and has immense potential to cut into profits. The researchers agree that the protection afforded to mammals fails to be applied to fish for several reasons, including large differences between humans and fishes, lack of knowledge regarding the welfare of fishes, and the greater emotional attachment of humans to other mammals.

As a counterpoint, the scientists argue that we should uphold the precautionary principle – a lack of full scientific certainty should not be used as a reason for postponing measures to prevent the possibility of serious negative fish welfare outcomes. This approach is widely adopted in environmental and public health management when working in areas of scientific uncertainty.  Meanwhile, some recent studies suggest that we should abandon the precautionary principle because the costs inflicted upon the industry would be too high.

The authors  point out that similar arguments were used against the animal welfare movements of the late 20th century when land-based industrial farming was questioned. However, the researchers welcome a discussion of opposing opinions as logical and well-formulated conversations are vital to progress in science. In fact, both parties seem to agree that more funding is needed in the area of fish welfare to provide robust empirical evidence and establish firm guidelines for humane and ethical treatment of fishes.

For animal advocates, this public discussion challenging the skeptics’ opinions further confirms the volatility of the topic. The precautionary principle, given the vast numbers of fishes who are slaughtered annually, is an important and timely point to raise. Despite the unavoidable resistance due to the financial implications of enforcing higher fish welfare standards, the strong scientific basis that already supports fishes’ ability to feel pain and sentience should be acted upon.