I live on the South West coast of England, (Torbay) I can understand your average commercial chap taking offense to the presence of a seal (one guy was taken to court for shooting a seal in the bay)
We dont get many of them, I have only ever seen one at a time near to the Torquay harbour. But its amazing how stupidly many anglers react to a single seal doing its thing, you'd think the seal had the plague or something...
As someone said earlier, they have more right to any fish than we do, they have to work hard for their food and survival, we fish for a hobby. You ought to congratulate any seal for figuring out the easy meal option, why should it it expend energy hunting when there are freebies to be had.
As for shooting them, do we want to get like the europeans who shoot anything n everything with a pulse (especially birds) just because we can or it MIGHT present a bit of competiton, and end up with lifeless enviroments.
Yes, sure, scare them away from your gear (harmlessly) its for there own safety as much as anything, but we really ought to look on it as a good thing that they are around, they do have a purpose in nature (as does everything) and just learn to accept them.
If your gonna have to shoot something, shoot the idiots on jetski's