About a month ago, the dolphins were extremely close to shore, like even closer than the line up. Anyway, when they're feeding sometimes the fish swim in towards shore to escape, so it was probably just a good size fish. I remember they were attacking everyone that day. My friend even had a big ass fish plop up on his longboard.
Speaking of fish and such in the lineup, one time I was (ashamedly) surfing north side IRI on a good day and I was the furthest person north. The water, about the size of a football field was bubbling and the bubbles were heading toward me so I got a little scared and jumped out. I realized it was a huge school of blue fish and I tried to yell to the guys that were further south to get out and one guy, when the bubbling got to him just started screaming, OH GOD, WTF!!! I'M BEING BIT! Crazy stuff. When he got out his foot was all bloody. Most likely not blues you're talking about but it just reminded me of the time that happened.
If you've ever caught a blue and released it from the hook, you'd see that they have some pretty nasty looking teeth! (and they do bite fingers and toes) that would account for the boiling waer, the bump, the dolphin feeding, and the bites! Just part of mother nature's food web! (just watch out for giant squid! - some wild stuff going on in San Diego)
i am way more worried about a bluefish getting interested in my watch or wedding ring than i am a shark. they attack anything shiny. they are like salt water piranhas. when i was a kid we would go to the outer banks and see the 'bluefish blitz'--where they swim right up onto the beach. those sharp little teeth look like they can take a nice hunk of meat out with one bite. ouch.