I understand rivers like the Oreti or Mataura have very high pressure, and the fish reflect this. There's always plenty of fish, because not many people kill these fish, but they're harder to catch than a less pressured river. These rivers don't seem to be referred to as fragile.

But sometimes a river that is very remote is referred to as a "fragile fishery". Almost no one goes to such rivers and kills fish, and being so remote they surely must receive less pressure than the rivers mentioned above. Sure a bit of chopper action, but not unrelenting mass driveby's every day. Is it the low number of fish that could make a remote river be referred to as fragile? As I see it, the worst that could happen is these fish become a bit more wise. I guess the extra stress of being caught and handled a couple of times wouldn't do them any favours, but still I wonder if this whole "fragile" thing is just locals being overly protective?