"how do u get rid of the seagull in big nate island poptropica?"?

You have to collect the old photograph that flies by the lighthouse. Once you collect it, give it to the man at the "Say Cheese" photo place. You swap the picture for a scuba gear. You go back to the lighthouse and dive into the oyster beds. You have to collect a lobster trap. Once you get it, give it to the old man on the dock. He gives you the lobster inside the trap and his jet ski keys. Climb all the way to the top of the lighthouse. There, you see the beacon. Use the lobster as a wrench. The light from the beacon will hit the seagull and it'll fly away.