Hi splinters,You should'nt believe all you hear about the ebro mate,most guides never use carp or lives for that matter,other methods far outfish lives anyway,its the anglers that catch and kill for food you should be worried about[immigrants] cause they dont care what size the carp is as a 40lb common will feed their family for weeks!!!
i dont use live bait for cats so it sounds like you have been misinformed by someone and having fished for carp passionately for 25yrs would not dream of putting a hook in one to cast out,i like taking hooks out of them!!!!!
hope this clears this up for you as i live in Riba Roja and know what goes on,some people will use lives but will generally use eels as bait as they last forever and obviously move and vibrate more in the river.
I certainly would not worry too much about the stock in the ebro,there is enough carp to go round,unless of course you are after catching the pasties mate