Quote:
Originally Posted by shrimpchips
both fish are presumably caught and handled so that effect should not be a confound. If they can see a difference, and there's no change to their baseline measures (while they might not be true baselines), then it's a fine measure.
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Sorry, I'm going to disagree with this. Though my disagreement is purely trivial, as it seems the cortisol levels are likely measured passively by collecting it from fecal matter, and not from being handled.
I doubt cortisol levels are being added on top of each other like you suggest and you cannot simply take levels from one group and subtract it from another. For example, consider you and I have the same level of fitness and I am sitting reading articles on canreef and you are currently going for a jog. You will have a higher heart rate than myself. Now, imagine that we both have tangs in a small tank, and the "tang police" are out for blood and decide they are out to get you and myself. Both of us will sprint as fast as we can to get away from nasty insults and condescending attitudes of the tang police! If you were to then measure our heart rate after we have been sprinting for a while, our heart rates would be similar despite the fact that you had been jogging whereas I was sitting. So, from our sprinting heart rate data alone it would be impossible to determine what our "baseline" was.
Perhaps a silly example, but that is just how I interpret it.