So, how does he know it's £10000 worth of fish? Did he weigh them out for the 'Eastern European thieves'? How does he know anything has been stolen?
What is the system he runs for selling day tickets; does he sell tickets to 'Eastern Europeans', is it effective and does he have bailiffs to police it?
And what's that camping sign all about; does he let Eastern Europeans camp and that implies overnight does it not?
Is he a bit clueless or else is he reacting to gossip and press hype?
On the other hand, it could just be another badly written press report.
Surely he has someone walking round the pond checking on permits.
PS. He could have just been a bit smarter and put up a sign in Polish saying 'No Fishing'.