Ethics & Suffering - Sentience and Cognition
There are many different definitions of sentience although put simply, it is the capacity for basic consciousness — the ability to feel or perceive, although this does not necessarily include the faculty of self-awareness.
The following link provides a comprehensive discussion on sentience in animals although for the purposes of this website we will focus on some of the key questions and how these are applicable to fish.
One of the oldest ideas in philosophy is that animals act in a machine-like fashion with no conscious thought processes of any kind. Charles Darwin was one of the first people to openly challenge this idea in his book entitled ‘The Expression of Emotions in Man and Animals’ (Darwin, 1872). Nowadays it is generally accepted that most vertebrate animals are sentient, although until recently the idea that fish are sentient creatures is one that has received less attention.
There are undoubtedly many different types and degrees of conscious awareness. If we move beyond the question of self awareness in fish and the fact that we are currently unable to categorically prove or disprove this, there are other aspects of sentience and cognitive abilities that fish have been shown to possess. Numerous studies have shown that fish have the ability to form mental representations with studies showing fish to be able to navigate complex mazes (e.g. Rodriguez et al 1994; ) avoid areas that place them at high risk of predation (e.g. Huntingford & Wright, 1989) and form map-like representations (e.g. Aronson, 1971). However perhaps the best examples of fish’s complex abilities come from nature, such as the ability for Atlantic salmon to migrate thousands of miles across the ocean before navigating back to the rivers from which they hatched.
There is also evidence showing that fish are capable of learning and memory from experiments that show fish can not only recognise and remember other fish, but also ascribe competitive abilities to these individuals (Metcalfe & Thomson, 1995; Johnsson, & Ĺkerman, 1998; Griffiths, 2003). Furthermore, a recent study provided evidence to support the capacity of trout to experience fear (Yue et al., 2004). This study showed that trout quickly conditioned themselves to associate the switching on of a light with the imminent arrival of a frightening stimulus (plunging a net into their chamber), which the fish quickly learnt to avoid by swimming through a doorway into a different chamber.
A common criticism of cage rearing systems typically used in commercial aquaculture is the fact that the circular swimming behaviour of fish in the cages is analogous to stereotypic behaviour. Stereotypic behaviour is a prolonged, obsessive, behaviour that can be seen in many animals when suffering. There is no evidence to support this claim although there are several studies that show beneficial effects of shoaling behaviour in commonly farmed fish species. Fish generally have a high level of plasticity in behaviour and they are capable of adopting different coping styles and life strategies in response to environmental factors such as water current speeds, stocking densities and feed availability. Just because the commercial aquaculture environment is generally very different from one that fish would experience in the wild, it should not be assumed that this automatically means it is detrimental to their welfare.
Fish are undoubtedly far more complex animals than they have previously been credited although much research is still required in the area of sentience and cognition. The preference testing and motivational studies commonly used in the study of terrestrial animal welfare need to be applied to fish farming systems to ensure that as many of the fish’s welfare requirements are being met as possible.The capacity to suffer is the most fundamental question relating to sentience and welfare and this is addressed in the pain and suffering section.