I've got it! He's talking about a Shiner that was brought (in this case as bait) by fishermen and then released into the lake. He must be catching them out of the lake for bait, so he's using that term since they are not native to the body of water they are now in.
He could be talking about golden shiners, too. Thats what they use when live-bait fishing for largemouth down in Florida. I know of one pond that has 'em in it.