This study does, indeed, seem seriously flawed, as bee venom is a complex mix of constituents that affect different parts of the body in various ways, as the following text ("borrowed" from a Web site) shows (my emphasis added):
"Bee venom is hemorrhagic, differing from snake (viper) venom, which is a coagulant. As well as containing: apamine, melittin, phospholipase, hyaluronidase, which have the opposing action of <b>inhibiting the nervous system<b>, and <b>stimulating the heart and the adrenal glands<b>; the venom also contains the mineral substances, volatile organic acids, formic acid, hydrochloric acid, ortho-phosphoric acid. Also present are some <b>antibiotics<b>, an enzyme ? phospholipase A, as well as two amino acids rich in sulphur methionine and cystine. Sulphur is the main element in inducing the release of cortisol from the adrenal glands, and in protecting the body against infections."
My own observations (far from scientific, I concede) suggest that fish hooked in the mouth do not feel pain in the same way we do. My reason for stating this is that I have caught carp from virtually unfished waters (and hence fish that are unlikely to have been caught before) and almost without exception they have hardly reacted to the hook going home. They tend to mill around, pulling against the tension of the line, but showing no "fight or flight" reaction that might be expected if the hook itself had induced pain. I do find, however, that they tend to go beserk as the net touches them or as they are lifted from the water. In contrast, fish I have caught from more pressured waters tend to react immediately to a hook, charging off in a panic reaction.
I would contend that this suggests that the reaction to the hook going home is a learned response, rather than a reaction to pain -- fish that have been caught before "know" what is going to happen to them. I'm am not sure that this is an entirely positive message -- the psychological cruelty issue might be an issue of concern.
Enough of this blethering.
I should be interested in other's views on this and if they have had similar experiences.