My old lab used to fish, he'd be swimming along in the bay, dive down (sometimes disappearing) and come up with a mullet. He'd also stalk up and down the pier and dive down of a school and grab one. Always mullet though. I never saw him catch anything else except for a couple of dying trout floating one the surface. The breeder I bought him from used to take the whole litter out in the river and tease them with a bumper and make them dive for it.