Y'all need to get yer syntax in order...

"Trolling" is both a sport and commercial enterprise. Sport trolling is performed with a single line/single lure (generally), whereas Commercial trolling is performed with multiple lines (6 in CA, OR, and WA, 6-8 in CAN, and 4 in AK) bearing multiple lures.

"Trawling" is also both sport and commercial, but "sport" is an odd word to describe this activity. In trawling (or "dragging", the colloquial term), a net is dragged through the water behind a vessel, with the mouth of the net being held open by a rigid frame or by the swimming action of "doors", two large plates that pull perpendicular to the vessel when towed.

For more on this and other types of fishing...plus a bunch of really cool other stuff...go Here

'Hootz