Next time you go there bring a garden rake with you. Go to the parts where you think there are fish and make several 2-3 ft wide hole in the mats. Come back the next day and from as far as possible pitch a t-rigged plastic of choice into the hole or walk your frog over the hole. You will almost always get a violent hit. This is a trick that i learned from a ol' timer and it is crazy how well it works. He keeps a metal garden rake in his boat for that exact reason.