The four charges followed the detention of the La Corua-based trawler last Friday by a fisheries protection vessel south-west of the Isles of Scilly.
Mr Nosti pleaded guilty to using nets with a smaller than permitted mesh; to under-recording quantities of megrim, anglerfish and saithe; and to not recording the correct net-mesh size. He admitted two separate charges of retaining on board undersized megrim and witch flounder. The court ordered him to forfeit his catch, gear and nets relating to the offences.
Meanwhile, William Waldegrave, the Minister of Agriculture, warned Spanish fishermen that the Navy would use gunboats to protect fish stocks in British waters and rigorously enforce European Union rules on fishing.
"We believe that we need tougher enforcement of the Common Fisheries Policy to protect the large fish stocks which Britain brings to Europe," Mr Waldegrave said.
"If [Spanish vessels] break the rules in British jurisdiction, we will deploy, as we have already, the fisheries protection squadron of the Royal Navy to enforce those rules."