Researcher Stephanie Yue of the University of Guelph in Canada shares her teams surprising findings on fish sentience and ponders the ethical implications.

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From: "BEKOFF MARC" Marc.Bekoff@Colorado.EDU
Sent: Wednesday, October 12, 2005 10:01 PM
Subject: What fish feel

What Fish Feel

Researcher Stephanie Yue of the University of Guelph in Canada shares her teams surprising findings on fish sentience and ponders the ethical implications.

It is not uncommon to find a variety of whole fish displayed on ice at any average grocery store. Yet practically every other type of meat is cut into portions and wrapped in clean packages that bear no physical semblance to the animal from whom they came. While most people in our Western culture would find it disturbing to see whole cows and pigs on sale for meat, most have no problem with the sight of a large salmon laid out in a similar manner.

A case of classical conditioningcued by a blue light signal, a trout swims through a door into an adjacent chamber in order to avoid an oncoming plunging dip net. photos: Stephanie Yue


Our emotional distance from fish may stem from the general feeling that they fall below the phylogenetic line where sentience begins. This may be because our present knowledge of assessing suffering in fish is inadequate in part because fish do not typically display traditional and obvious signs we are familiar with in other animals. They are not capable of facial expression, nor can most species of fish vocalize; given their general anatomical structure, changes in body posture are extremely limited. Consequently, their use in scientific experimentation, in place of birds and mammals, is seen as ethically acceptable.

Overcoming Taboo

Its not surprising then to see that, according to statistics provided by the Canadian Council on Animal Care, there is a rising trend in the use of fish in research. In Canada, there was a 463 percent increase between 1975 and 2002, resulting in over 600,000 fish used for scientific research in 2002. Fish consumption has also risen steadily, mostly due to increased interest in a healthy alternative to traditional protein sources such as beef, chicken and pork. Huge numbers of fish are used by humans on a regular basis.

However, recent anatomical, physiological, neuropharmacological and behavioral studies suggest fish can suffer in ways similar to "higher" vertebrate animals. Considering the large numbers of fish we use, these
findings should be enough of a reason for us to consider their welfare as a serious matter. In addition, animal welfare should be defined by how an animal "feels"not just by how well it physically copes with environmental conditions such as absence of disease, lack of injury and good growth.
Since sentient creatures have the capacity to subjectively and consciously experience things, it makes sense to investigate the fishes capacity to suffer.

This is the project our fish welfare group at the University of Guelph is currently undertaking. It is not a trivial endeavor, for whether fish even possess the neuroanatomical structures that generate the phenomenon of consciousness is still a subject up for debate. The topic of consciousness
has had a tumultuous history itself, and it has been less than a couple decades since words like "consciousness" and "sentience" have reappeared in scientific animal literature. We are only slowly overcoming the taboo of studying conscious thought processes and voluntary behavior.

From our studies on highly domesticated rainbow trout, we have seen these fish show behavior that is much more flexible and complex than was previously acknowledged. We have found that trout have some cognitive capacity that rivals that of mammalian laboratory animals, like rats. They not only show the ability to learn, but they also have memory of the things they learned so they can anticipate events and adjust their behavior accordingly. This means some of their behavioral repertoire is "purposeful" and lends evidence toward "conscious" behavior.

Analyzing Fear

Not unlike a rat who will press a lever for a food pellet, the trout in this photograph presses a pendulum for a food reward during a recent investigation of fear responses in rainbow trout.


Most of our experiments delve into the phenomenon of fear. We try to tease apart which responses to negative stimuli (in our case, an oncoming dip net) are likely to be reflexive and which are deliberate. These experiments often require fish to be trained in tasks ranging from simply swimming away from an area where an aversive stimulus resides, to highly artificial and relatively sophisticated tasks such as pressing a lever in order to obtain a reward.

We found that trout follow similar behavioral patterns when frightened, as do other animals like mice. Mice show avoidance, fleeing, freezing, and scanning of their environment and general decrease in activity followed by
gradual resumption of normal behavior. Mice are deemed sentient animals with the capacity for a range of subjective experiences. Why then should these same behavioral patterns, when seen under similar experimental
paradigms, not be employed as evidence toward the possibility of subjective experiences in fish?

There is more evidence that fish do have some level of consciousness than there is evidence against it, and it is logically more likely that fish are sentient animals than they are not. What level of consciousness they possess, however, remains to be determined. We still have much to learn before we can properly generate guidelines specifically tailored to the needs of different species of fish kept in captivity. Yet we are moving in the right direction by entertaining the notion that fish may indeed be worthy of more moral consideration than they have had in the past.


This research project was made possible through a grant from Animal Welfare Institute and the Center for Alternatives to Animal Testing.