Those are great ideas guys, but I have only seen Humboldts close to shore 5 or 6 times total in my life. They seem to be on the move when I see them looking for something. There are lots of shrimp boats around now and the fishing is real good. They were all small ones 1m and under.
If I see one in front of the house again I will take a pic of it. My wife saw one when she was out looking for clams and scared it to deeper water because she was afraid of the gulls sitting on shore waiting for the little humboldt to make a mistake.
From what I have observed the Humboldt seems to take any opportunity to feed on anything it can. If it means heading into the shallows to eat a blue crab or flounder when you are young, well then I think that they are more than capable of doing it. Who knows maybe the small ones spend lots of time in the shallows before they go deep when they get older?
Like I said, Im not a researcher I just report what I see.