Ancient Megalodon difficulty on the brig

I mainly fought them on sloops and gallys, and they were usually pretty easy, maybe the Dread was a little long but nothing too awful.
Today when I was fighting the Dread he was extremely overwhelming, charging almost non-stop an spawning crawlers all the time, I don't think it's supposed to be like that.
Has anyone else had a similar experience?
Edit: I think it's ALL megalodons actually