Martin gives an authoritative answer. That was what I was implying. There would be no official records of prizes being sold in Spanish ports. It is likely that is how many were disposed of, but there is no way to prove it or not now.But I think.. I have not evidences.. but I am sure... in America.. Spain, France, Britain always were in a non-declared war.... in 18th Century.. so.... I guess....they sold prizes....in a kind of "black" market or a kind of "non-official" way.
But in 1861 - 1865.... Spain was not in war with USA.. Certainly Spain and Confederate relations were good ... and Florida, Georgia, Alabama and Louisiana maintained more than cordial relations with O´Donnell and Elisabeth II´s Spain... and Cadis and Havana harbours.... were not unknown to the Confederates ..
So.... Could they sell prizes in Spanish ports? Difficult to say... legally it was necessary to be in War... And Spain was not in War... but... it was a Civil War....So... I have the hunch.. Confederates sold prizes in Spanish harbours.... and the authorities blinked an eye! But not official data.
There isn't as much discussion of Spain's position on the ACW as Britain or France's. Spain had slavery and royalists generally were sympathetic to the Confederacy. It was also in Spain's interest to break up the US. Spain was pretty ambitious about maintaining and increasing its territory and influence in the Americas, and could not get too involved on either side.