Ever thought of adding other non lure taking fish, water birds and insects?
Many times when I’m out fishing i see a large unidentified fish and start frantically casting my lure at it only to eventually realise it’s just a massive Carp cruising by.
Also the larger predators should be attracted to the smaller fish as well as the lures! It would be great in the game to see a large pike strike at a nearby smaller fish.
Also simulate spawning activity and shoals of fry at the right times of year, so the fish in the game actually breed, reproduce, grow and die almost like a little virtual ecosystem going on. That way the fish population would be constantly fluctuating and never the same.