Nope, they just wanted to keep the trout away from the poor people.

Using a snare is possible too I am told. Like tickling, but you slide the snare over from the tail end up to the gills.

There are lots of 'poachers tale' type stories like this inn the UK.

Are you sure? Fishing in my neck of the (American) woods requires a $25 license every year, and even the poorest families in my town get them, because it's just that profitable to supply yourself with fish for a whole year.

The money is used to protect the rivers and water bodies from foreign predators and pollution, so that those families can rely on this source of food for decades to come

Yes. Hunting/fishing rules/regulations in most of Europe reflect a society where (until recently) only the upper classes owned land and it was illegal for commoners to take any resource from that land without the permission of the landowner