Last week we travelled down the Loire from Sully sur Loire all the way down to St. Nazaire on the coast. 440km in all. Even at Sully which is about half way down, the river is massive. Well over 100 metres wide. It is also very clear and runs for the most part through a sandy area meaning that the river is very shallow in places with one or more deep channels. It also means that in a lot of places the actual river is miles away from the access roads. A bit like Cleethorpes when the tide is out
Species wise; barbel, zander, catfish and the ever present carps.
I never got the rods out all week. Too busy sight seeing.
If you search on "carte de peche" and add the department number, then run the result through a translation service you'll get an idea of what to expect.