I can tell you that the Saugus River to General Edwards Bridge will hold Winter Flounder, Window Pane Flounder and Summer Flounder. It will also hold Taug and some have reported Sea Bass but I personally have not caught a sea bass out there.
The big bait fish, Pogies, will make a prescene there from time to time, their arrival can be now-September. You'll know there are pogies there when you see the pogie boat at night, gill netting. Big bait, big bass.
IMO, if you are experienced enough and can perform a self rescue, start fishing the Saugus River at night. A 3/4oz jig head and 9" black sluggo or 13" blamber hogy, Kayak, and fish finder can do a lot of damage in there. Cast and drift the river. All those little bends. If you don't find large, then it's time to head out front and explore places, like Nahant, swampscott, marblehead....the list is endless....you got the kayak, go get the fish. It's that simple. Buy a Santini Tube in Red, 2 dozen worms, start at 6am and fish till sun down. Troll the rocks on the northshore. I guarantee you 40lbs before the season is over. But you have to put in your time. These rocky areas from Nahant to Gloucester is a kayak fishing mecca. I spent countless hours in that vector and have caught a boat load of large....but no one is going to hand it to you. Happy hunting and be safe.