Ive found most of my estuary fish are caught near the shore or rocks, or a reef structure or bridge pilots etc, that's where the cover is.
Flathead and flounder are flat for a reason. So they can hunt in shallow water.
Over 20 years ago i was fishing near the rip bridge one night north east side near the first jetty.
and was casting in every direction had a few rigs out, and a fellow on the shore was reeling in a bait, it got smashed by a huge flathead near his feet about 2 foot from shore.
Getting off topic= later that night a small tinny with an 70 year old fellow and his son went to anchor in the middle of the rip east of the bridge.
as soon as their anchor hit bottom the force of the water pulled the nose of their boat under.
i had to pull anchor reel lines in and motor over to save the old guy.
i jumped over the side and lifted the old guy while a mate in the boat heaved him in.
just put that in coz I remembered them fishing in the middle of deep No mans land.
anyway getting back to it,
thats when I learnt that a lot of fish hunt near the shore.
goes to figure that baitfish stick close to shore for cover and that's when predators get in close to hunt them.
So when in a boat I cast towards the shore or rocks n bridge pilots etc,
as the deep water is usually void of fish.
just my opinion though!