Ascribing sentience to fish: potential policy implications

5. Counting fish in tonnes

Terrestrial livestock rearing systems calculate breeding, production, and mortality rates in terms of numbers of animals, often referred to as headage. For example, the Scottish Agricultural Census gives annual figures for the numbers of cattle, sheep, pigs, poultry, and deer being farmed in Scotland.

It is unlikely that this method of counting is employed purely to acknowledge the status of each of these animals as a sentient individual, and the very large numbers involved in some production systems would tend to preclude this. However, counting animals in numbers does allow for such acknowledgment and does give the public some impression of the living individuals that are bred, raised, and slaughtered for food production.

This contrasts sharply with the method of accounting for fish taken in commercial marine fisheries, where the statistics are traditionally recorded in tonnes. For example, in 2022, Scottish vessels landed a total of 376, 233 tonnes of pelagic and demersal fish^[102]. While it may be difficult, or even impossible, to record marine fish numbers at the time of their capture, if this calculation were to be made, the number of sentient individuals taken would be better understood and considered.

In Scottish salmon farming, the final production or ‘harvest’ of fish is often reported by tonnage, although numbers are also provided. The most recent Scottish fish farm production survey gives the total production of Atlantic salmon during 2023 as 150,949 tonnes, a decrease of 18,245 tonnes (11%) on the 2022 total^[103]. The total number of smolts put into sea cages in 2022 was reported in numbers, at just under 55.3 million individuals. Fish escapes are also counted in numbers^[104], with two incidents involving the loss of 80,001 fish from seawater Atlantic salmon sites in 2023. There were 13 additional incidents reported where the companies confirmed there was no loss of fish^[103].

Salmon farm mortalities during the period at sea are counted in numbers and reported by the Fish Health Inspectorate (FHI)^[105]. The mortality data show the numbers of dead salmon in each incident but not as cumulative totals, such as annual figures.

While the numbers of fish involved in all stages of farmed salmon production are extremely large, the reporting of escapes and mortalities by fish numbers suggests that it is possible to compute these incidents in terms of individuals, even if there may be an element of estimation involved. Therefore, it appears feasible to report statistics both for fish captured at sea or harvested on salmon farms – even if notionally – in terms of numbers rather than tonnes, thereby recognising the intrinsic value of each sentient individual.