Freshwater Fisheries, Friend or Foe to British Wildlife?

I have recently read numerous tweets from supporters of British wildlife painting all freshwater fisheries owners and anglers in a bad light, over their views on the control of sport fish predatory species as well as other deaths attributed the sport of angling.  I find this opinion that everyone associated with freshwater fishing has the same views to be very presumptuous and narrow minded.  I appreciate that there are some people associated with angling that would not hesitate in injuring/killing any predatory species hunting in their local fishery or discarding their old line on the bank etc, but these individuals i believe are the exception to the rule within the angling community.  But  rather than slating fishery owners and anglers, supporters of British wildlife should be congratulating them on their assistance in maintaining biodiversity within the British Isles. Without freshwater angling i feel that that British wildlife would be in a lot worse state than it is at present, given that freshwater ecosystems are ecologically important habits within the British Isles.
With the increased popularity of freshwater angling over the last 30 years or so the number of fisheries has increased significantly throughout the British Isles, combining this with decreased effluence pumped into our rivers and canals connectivity between pollution free waters has grown throughout the British Isles, allowing once isolated populations of flora and fauna greater colonization opportunities.  Whilst this expanse of freshwater fisheries has provided greater connectivity and colonization opportunities, not all species utilizing these opportunities are welcome within the fisheries.  Species such the Europen Otter (Lutra lutra), the Cormorant (Phalacrocorax carbo) can have a devastating effect on inland fisheries in a very short space of time.
I do have first hand experience of the damage such species can do, only 2 days ago an otter got into the lakes i help manage and we lost a couple of very large carp, so while i would never condone the killing of any of these species i can understand why the owners of fisheries would want to kill them.  If you had invested £100,000 into a fishery, wouldn't you want to protect your investment?  I appreciate you could argue that security methods such as fencing can aid protection against otters, but if the lake/complex is huge the cost involved in controlling them could be astronomical/nonviable and you may still have to address an aerial threat from Cormorants for example.  So knowing the risks involved it begs the question why would anyone want to invest so much money into a fishery knowing the risks involved?  Personally i believe that the vast majority of fishery owners and anglers are keen amateur naturalists and like nothing more than strolling around their local fishery and enjoying the diversity of life it supports, but i appreciate its not a view shared by all owners and anglers, with the later being the biggest culprits.
Some anglers i have come across over the years have had no appreciation for the environment their within and have witnessed them leaving rubbish (including fishing line), throwing stones at wildfowl, throwing fish back into the water and killing fish etc, but as i wrote earlier these people are the exception to the rule.  So when i read wildlife supporters (as i am myself) saying that they hate all anglers and fishery owners, it frustrates me hugely, and i wonder if these people have actually thought their views through at all or are they what i personally call "fluffy wildlife lovers" supporters who like all the niceties of nature but would try to stop a magpie from taking a young duckling etc.  Personally i believe that although there are some serious issues associated with freshwater fisheries and their impacts on our native species, but the benefits these fisheries offer to our native flora and fauna far outweigh any negatives and the vast majority of fisheries should be applauded for their work.
When i hear that fisheries owners have killed/ want to kill some predators to protect their fishery i can sympathize with their view even if i don't totally agree with it, but if it was your fishery what would you do?

I would like to thank anyone who has taken the time to read this and just say that these are my own personal views and i realise that many people wont agree with me.