I'm not anti-fishing per se, it just pisses me off sometimes.
My reasons:
There's a lake around here in a country park, the rights belong to a fishing club in a nearby city as opposed to the town the lake is in. The fishermen have tents and fishing rods sprawled out all over the beaches (there's sand) and act as if they own the place. Despite it being a country park people often can't take their kids to the beaches beside the lake or let their dogs go for a swim because of a few out-of-twon fishermen giving them evil looks. Hence the locals are being turfed off what should be their "common land" if you like.
The canals and rivers are often taken over by people fishing too
On most rivers you can't row a boat or take a canoe because of fishing clubs and their water rights. What sort of a country are we where we give rights ownership of rivers to private clubs?
I see it as largely pointless. Most anglers throw their catch back in either alive or dead. What's the point in that? If you're going to hunt then stop wasting your time and actually eat the damn thing instead of teasing it and playing with food. Sports hunting which most modern angling comes under is stupid, keep racing pigeons or something if you have a competitive side, if you fish to get outdoors then take up bird watching.
On the other hand I do like this about fishing though:
It gets people interacting with nature and into the countryside
Angling societies maintain fish stocks and try to keep rivers clean which is good for all of us
The land around waterways is often semi-woodland and preserved for the enjoyment of the anglers and often the public too. Without the fishing lobby our rivers would be a lot less clean.