Chasing them can be tough but there are a couple of indicators that can help you zero in on a school. Birds circling or perched near by is a pretty good sign that there's a school near. Circular disturbances in the water is another one. It's kind of difficult to explain in words, but on calm water you'll notice a section that's not like the rest. You'll figure out your go-to spots and one of them will usually produce for you each time.