Hi Chuck,
I just took a look at what the walkthrough says about this section of the game:
The Eastern Promenade: Jump to promenade. Go forward twice. Click on hole of tree.
Go fish: In inventory combine the fishing hook from Gerard's office with the fishing line taken from gazebo to get hook on fishing line.
Combine the hook on fishing line with pull rod from basement of Gerard's office to get primitive fishing rod.
Use primitive fishing rod on the hole on tree. Get a tool extension.
It looks like you have to use the primitive fishing rod on the hole on the tree. Have you tried putting the fishing rod together and then using it on the hole of the tree?
And if this is of no help, what does it say when you click on and consult your journal?