"Don't feed the trolls" was a useful thing to say back when the word meant something far more specific than just "someone behaving badly on the Internet."
Now a troll is just an asshole on the internet.
They imagine "troll" as a metaphor invoking the humanoid creature from Scandinavian folklore, which, in the Three Billy Goats Gruff story, is a nasty, unpleasant, violent creature who wants to eat everyone who crosses his bridge:
https://en.wikipedia.org/wiki/Three_Billy_Goats_Gruff
Hence the asshole angle.
According to etymonline.com, the etymology of "trawl" is:
1560s, from Dutch tragelen, from Middle Dutch traghelen "to drag," from traghel "dragnet," probably from Latin tragula "dragnet." Related: Trawled; trawling.
Now, "troll" verb:
late 14c., "to go about, stroll," later (early 15c.) "roll from side to side, trundle," probably from Old French troller, a hunting term, "wander, to go in quest of game without purpose" (Modern French trôler), from a Germanic source (compare Old High German trollen "to walk with short steps"), from Proto-Germanic truzlanan.*
It's rather related to "stroll". Nothing in the semantics about fishing.
I suspect that "troll" in longline fishing in fact refers to the long line with many hooks being pulled around; i.e. "trawled".
The ultimate troll is a well-timed and placed piece of copypasta, which at ctrl-c ctrl-v is impossible to beat.
There is no such thing as a "fishing troller".
I assume you are thinking of a "fishing trawler" which catches fish by trawling.
Trawling: to fish (the sea, an area of sea, etc) using a trawl-net. Trawl(-net): a large bag-shaped net with a wide mouth, used for catching fish at sea.
That said, to troll is also a method of fishing, but involving a baited trailing line rather than a net.
Personally I have always interpreted 'troll' (the noun) in the mythical under-bridge-dweller sense, and 'trolling' in the 'to stroll or saunter' sense. That is, the troll has emerged from his bridge and is now strolling around looking for victims.
> > The shop told me that Dacor and Scubapro have good reputations for > > stocking spare parts for all their products, no matter how old. > > This does cause their prices to run a little higher.
> (Gosh--this looks like a troll for a flame-war. I couldn't help > but visualize myself standing in a used car lot.)
Here it's pretty clear that it's being used in the sense of someone dropping a lure, a bit of tasty bait.