The argument of the icthyologist previously quoted seems quite dubious to me. The argument, that is, that fish respond to aversive stimuli but do not have an awareness of pain because they lack the parts of the brain that are involved in awareness of such things. He points out, for example, that patients under anesthesia respond to aversive physical stimulation but are not aware of pain.
First, to the degree that the ability to be aware of pain is something that has been selected for or is associated with other things adaptations that have been selected for, there is no reason to think that all species solve the problem withe the same neural substrates. For example, in humans, memory is a function of specific brain regions. The neocortex and certain limbic structures in particular. Learning and memory are adaptations with great survival value however, and other species have come up with ways to accomplish this in different ways. Bee's, for instance, are very good learners, but don't even have what most people would call a brain, much less a neocortex.
Secondly, although it is a bit of an aside, no one has any idea in my view whether or not one can feel pain while under anesthesia. Certainly you do not remember it if you do, but that doesn't mean you don't feel it. In addition, there is a bit of a more philosophical, but real nonetheless, issue of who we are refering to when we talk about awareness of pain and other things. The part of the brain that does the talking may be shut down during anesthesia and may not be aware of pain, but studies in split-brain patients (which appear in some ways to conist of two selves in one skull) have revealed that some parts of the brain can operate independently without having access to linguistic centers. Can these areas 'feel' pain? Probably, but they would not be able to tell you if they did. and talking to someone thus affected, you would never know that they were feeling pain (depending on where the pain stimulus was delivered) because self-awareness of such pain could be limited to the half of the brain which is incapable of communicating with others.
In any event, all I'm saying is that no one knows if a fish 'feels' pain, or what the conscious experience of an aversive stimulus is to a fish. And I doubt that anyone ever will. Of their own volition, they bite down on bony fish and swallow them hole and so on. I suspect that they do not have too many pain neurons in their mouth so I don't know how bad hooking them really is. Moreover, many of them do the same thing to other fish that we would do to them, so in a sense, by eating one fish (and perhaps inflicting pain on it in the process), other fish are spared a similar fate.
They do taste good.
-d-
