No need, I've just salvaged my 8 new fishing poles (nothing but polysteel, I'm going to suggest fishing lines to Kinak though).
Didn't get any dropped items the first seven times.
Killed a dockhand (charged the crates) in case you needed to kill the new pole's owner, but nothing on the next "fishing spot" encounter either. Oh well. Continued to fish and charge at crate unloaders, but nothing in the next two encounters.
I then charged the chatting dockhands since those were the ones who definitely fished at that spot. But no dropped items on the next encounter either.
I'm pretty sure I've been stuck at "comfortable" fishing level for this entire time, I don't think I've even got a "you got better at fishing" message, even with training hooks… or does that only happen pre-skill?
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As a side note, I noticed the dockhands also discussed their favorite TV shows, so I set up a descrambled TV and watched it immediately after passing my thermos around. I did get an unusually maritime version of the crazy man show, but nothing we don't know about:
"singing fishmen that lure dock workers to their doom, voodoo zombies from beneath the waves, and flesh-hungry ghouls on the waterfront! It's the end! The end of times!"
Tried it again on both TVs with some other mundane results, so I suspect it was either a funny coincidence or a bizarrely subtle 1/day thing just for flavor. (They also discuss "work" and "sports", but that seems too vague. I'll try Sports Blogs.)