Ascribing sentience to fish: potential policy implications

4. Principles applicable to fish as sentient animals

As SAWC has previously stated^[1], promoting animal welfare means increasing positive experiences and reducing negative experiences. Humans have a moral obligation to have regard for evidence of animal sentience, and human activity should consider the impact on animals who are potentially sentient, in order to prevent or reduce unnecessary suffering. In practice, we should adopt a precautionary principle in seeking to avoid suffering, except where this disproportionately increases the risks of suffering for other sentient animals.

Considerations relevant to the welfare of fish, as sentient animals, include:

• physical health;
• environmental quality (e.g., water quality);
• resources including 3D usable space and enrichment;
• the ability to predict, evaluate and control their behaviour and environment;
• stocking density;
• the impacts of previous negative and positive experiences on learning;
• inter-individual conspecific relationships (both antagonistic and positive for gregarious species);
• pain relief;
• individual preferences;
• handler competence;
• monitoring;
• stress;
• humane slaughter;
• impact of recreational fishing practices including catch and release.

There is no biological reason to disregard fish sentience. However, there may be contingent biases against such regard^[94-97] including:

• humans may be less able to empathise with fish, due to our weaker ability to recognise piscine emotional expression, given their behavioural and anatomical differences (e.g., humans rely on facial and vocal expression), their lives are spent underwater^[98] and most humans lack significant experience in interactions with fish as individuals;
• humans may have different affective responses to fish, for example, they may be seen as less ‘cute’ than some other species or because of particular human affective responses to species such as sharks;
• much of what occurs to fish is unseen because they are underwater and, for most people, unobservable;
• some fish are small, especially as juveniles, notwithstanding that size is not a criterion for moral status;
• historic myths about fish cognitive abilities (e.g., goldfish’s memory), which have been disproven;
• many fish have large numbers of progeny with low initial survival rates, irrespective that this is neither relevant to the moral status of individuals, nor does it take account that those which reach adulthood can be extremely long-lived. For example, the wild flapper skate (Dipterus intermedius), a large cartilaginous fish studied and tagged for monitoring purposes off the west coast of Scotland live in excess of 40 years^[99] and famously another cartilaginous fish the Greenland shark (Somniosus microcephalus) may live in excess of 400 years^[100]. Typically, bony (teleost) fish live shorter lifespans, but nevertheless these commonly range from 2-30 years, depending on the species^[101];
• fish are killed in large volumes and in ways that make it difficult to count individuals, and often quantified in terms of total weight rather than the number of individuals affected;
• cognitive biases that recognising fish sentience and suffering might be inconsistent with our historic and motivated practices, such as commercial fishing and aquaculture practices, angling, or fish consumption, in order to avoid criticism of, or changes in, those practices.