<blockquote class=quoteheader>Bill Cox wrote (see)</blockquote><blockquote class=quoteheader></blockquote><blockquote class=quote>
Its all a matter of choice mate , you fish for what you want to catch!</blockquote>
It's not just a question of choice, it's also a question of morality; how we judge what's acceptable in our sport. Would it be OK to buy a great white shark and put it in a pool of seawater to be caught again and again? Or, in a shooting analogy, fill up a cage with roe deer so they're easier to shoot? And if we did catch that shark or shoot that deer, is that sport?
I'm all for freedom of choice, but I worry that making fishing easier doesn't make it better, and that, if we could catch captive salmon, say, we will begin to forget the big problems facing wild salmon. I'm not moralising, I must add, about this sturgeon or the bloke who caught it, but just asking people to question whether holding fish in an artificial captivity in which they can't behave as they have evolved and then catching them again and again is any kind of angling advancement.
Roach, rudd and perch are all native to the UK, and - importantly - are adapted to live in lakes and rivers in the UK. Where they are not deliberately overstocked, they can feed, breed and maintain a population unaided. They are in every sense wild fish, living naturally. Carp are, as you say, introduced, but I can find no reference which says they are river fish; maybe you could post a link. I think they have always lived in both lakes and rivers and, once again, they can feed, breed and look after themselves in our waterways.