I have no doubt that there are more around than we see and hear about. The problem will arise "when" the seals migrate up this way and establish a second (or third or.....) rookery (breeding station) farther north. That may be when the sharks take on a more noticeable role in our local waters. That's when swimming may become prohibitive due to the "potential" danger, but that will be some time from now.
One point to consider: There has been a lot done to help clean up Boston Harbor and the surrounding waterways, and with that success, we have invited fish (and mammals) to repopulate areas that were void of life decades ago. With this increase in fauna in our coastal waters, it would be foolish to expect any predator to NOT visit our waters, seemingly loaded with food for the taking.
As the saying goes: "Be careful what you wish for, for youi may not like what you get in the end!"
Personally, I think the sharks are cool. They have every right to be here, and may actually help with the seal problem, not as much with eating them, but as an ever-present threat of attack.
Now if we could only teach them to eat plovers?
