This will result in the angler reeling in the cash amounts and adding them to your current running total in the feature. Once activated, the basic premise of the bonus games is to land cash values (often in the form of a fish) simultaneously as a fisherman. Instead of the developers wasting any valuable RTP on insignificant bonus features in the main game, they would rather save it for the free spins round, which is generally triggered when three or more scatter symbols appear in view.
More often than not, in any fishing slots you come across, you'll find the base game lacks any real modifiers or bonuses.