Carbincopy I liked the old way to hold and release to control cast.
When you hold, you go with the fish line/rope (I do not know the correct name in english) until where you want, and when you release the fish line/rope come back in auto reel and could take the fishes (it will be a better animation). I think this kind of game has potential.
You could put some boots, tyres and garbage and when you take some of them you could take more points for cleaning the ocean. they could stay at the bottom of the screen and do not move.
another bug, when you catch the fish and cancel with double tap the fish is released free. You could put some kind of boolean variable, when you catch a fish you put it true and can not cancel the action with double tap.