As being one of those "dreadful foreigners"

and also as an ex-fisheries officer (in Poland we have a volountary service, so anybody willing to spend their time and money can guard their river or lake, after attending to a course and passing a test) and a fly fishing journalist I have a few ideas.
First - establish some laws regarding sea fishing - size and bag limits, like minimum size of f.x. 30cm and bag limit of 3 fish per angler. Than, some closed season, like for bass, during the spawning season. Than, you will have a good legal base to call IFI or gards if the law is broken. For now they are not doing anything illegal, though behaving senceless, there is no legal basis for even talking with fisheries officers. Than, launch an information campaign in media, gain contact with local fishing stores and newspapers. Than - there be no excuses like "me no speak english" - it would be breaking the law with every consequence of it.
Similar aproach was taken by freshwater fisheries - ban on taking pikes over 50cm etc and this seems to give basis to prosecute individuals with the lack of imagination connected with their actions and many of such actions were taken, with people fined for thousands of euro for killing a large pike etc.
And as for complaining about foreigners, especially those from "eastern Europe" (learn geography please, eastern Europe is Ukraine, Russia etc, not Poland, Czech and other EU countries) - I know that they cause problems, but I also see that they (we?) have become an excellent "finger pointing" excuse to not to blame local anglers and autorithies for some problems. So often I read, even here, how "foreigners" are emptying waters, how "they" should go home etc... But honestly, similar problems were here (I live in IE since 2005) before imigration and some local guys behave more or less the same way.
For example - only unpleasant situation I had here when fishing was around 2006. Some lads came as I was relasing a large pike, almost a metre long fish and start asking me to give them the fish. I told them politely that it would be illegal as the fish of this size must be returned. then they started to be very aggressive, I've heard that I'm a f..kin immigrant etc. I know that they are fishing in the area, as I've seen them few times on the water. So though it is a big problem, you shouldn't blame foreigners everytime for every problem with overfishing, rubbish etc, as more than few local lads do the same, at least in midlands. I'm not trying to say that foreigners are not a problem when it comes to fishing, more like that such a behaviour (or just call this simple - stupidity) don't have a nationality and should be adressed by the most interested - the anglers. Problems ignored don't seems to vanish, more like to multiply

I think that the worst thing is when guys like you do nothing with what is happening on your shores. Really much can be done if only there is someone willing to spend a time and some effort to change what he or she doesn't like or want to see - f.x. how effective "green people" can be in inposting eco laws etc.
If you need any help with translations etc - I'll be more than happy.
For years now we try to educate fellow anglers in Poland about necessity of Catch and Release and more sporting behaviour etc, but we are starting from a tough position

If I can only ask - please do not generalise, as there is plenty of really ok guys from outside of IE, releasing almsot every fish and catching a lot of them. There is no such thing as "they" responsible for "everything", the same as not every Irishman is a catholic or a farmer, though many are. In majority immigrants here are rather peace-minded, no one should "pull a knife on ya" - in fact more often immigrants are stabbed to death by Irish, than vice versa

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All the best!