Quick and simple suggestion.
Fish nets:
The fish net is an attachment that comes two sizes, small and large. The can attached to either the side or front of the ship and will periodically collect fish while the ship is moving (it must be moving in order to catch fish). Small nets can only collect between 1- 2 fishes/items at a time while large nets can collect between 1 - 4.
Fish nets will also have a chance to collect random items in sea as well as fish, however it will not be able to collect sunken items as opposed to a fishing rod since it is all surface level fishing and as to not take away from fishing rods.
Bait coatings:
Players will be able to apply different bait coatings to the net in order to attract different fishes. For example coatings to attract specifically sharks, small fish, exotic fish etc. These coatings will have to be applied before the net is attached to the ship (shark bait net, alluring net etc.)
Reinforced nets:
These are special nets that are necessary for the dark sea. Normal nets will not be able to withstand the dark seas weather. These nets can only be crafted using high level materials and therefore they are very rare and expensive.
Net launcher:
While travelling the sea, your crew may notify you of the prospects of treasure below. They will recommend using a net launcher once you’re in the vicinity.
Net launchers are fishing nets that can be detached from ships while the ship is stopped, these nets will sink down and have a chance of collecting a lot of fish and even sunken (and other items located lower in the sea). However, in order to collect the loot the player must swim down and manually collect the net and bring it back to the ship in one piece.
A detached net will take 5 minutes to respawn (to be used again) if not collected and will be lost upon death, however if a player dies before collecting the net then they can still collect the net as long as it is within a 5 minute period of releasing it. Bringing a net back successfully will respawn the fishing net. The longer a fishing net sinks down the better chance at a higher yield. Fishing nets cannot be launched on shallow waters.
Using a net launcher when the crew recommends it will increase the chance at better yields.