Birds Baitfish school question

[silver_snipe]

Yesterday I was outside the east Cameron jetty and started fishing under a small flock of birds. something had baitfish pushed to the surface in a big dark ball and would sometimes attack the ball on the surface. I started fishing with a gulp swimming mullet (simply what was tied on) and whatever had the bait balled up would bite the gulp in half just behind the hook. When I say bite it in half that is what I mean not pull or tear it. Any idea what had this bait ball? My thought based on the gulp being bit in half was probably some type of mackerel. The bad thing is had a guide boat push me off this school before I could change up tactics and maybe catch something.