Have you fished in a trout stream that has clearly been flogged? We've all had those days when we have been trout fishing and there's foot prints along the waters edge and not a trout to be seen, so we quickly jump to the conclusion that the trout stream has been flogged.
Fishing pressure can and does have an impact on trout numbers in streams, but often it is not nearly as much to blame for the poor trout fishing as many people might assume.
Trout need certain environmental factors to thrive in streams. They need deep pools, cold water, cover over the water, decent water flows etc... Trout can not survive in streams where the conditions are not favourable.
For this reason, quite often it is the habitat, or lack of suitable trout habitat that is to blame more than anything.
The better the trout habitat is, the more trout the stream can hold and the more fishing pressure the stream can withstand.
For example, you could have 2 streams only kilometers apart, exactly the same size. One has excellent trout habitat, and one has poor trout habitat. They both see the exact same amount of trout fishing pressure. The stream with the better habitat will fish much better for much longer. The stream with the poor habitat will end up flogged much more quickly because there wont be as many trout in it to start off with with because of the poor habitat.
So next time you have a bad day on the water, before jumping to the conclusion that the trout stream has been flogged, ask yourself "Is this suitable trout habitat? Is the water shaded with plenty of cover? Are there a lot of deep holes in the creek?"