I believe the ability to track fishing nodes was planned at one point, and has been requested frequently, but in general there isn't a way to consistently predict where they will be (they move around) so it was never added.
Fishing nodes used to be there, but some problem caused them to be turned off, and they haven't been re-enabled (I still have fishing nodes in my database!).
Iron Chef Japan music . . . If memory serves, I believe that the fishing tourney tastyfish pools / nodes do respawn in the same spots. "Yes, the Iron Chef is mixing tastyfish offal with oilyfish bag of offal to make offal of joy ice cream. "
And while I don't argue with you there, I think they're still classified as fishing nodes, and every other fishing node in the game moves around a bit. Enabling tracking of those would enable meaningless tracking of a lot of other things. I could be wrong here, though.
Hirsuit, I dont think Gatherer itself ever tracked fishing nodes. However fishing buddy did use gatherer to store locations not long after fishing nodes were added, not sure if it still does or not.