Sure. Here's where it says it is illegal to catch atun rojo (bluefin) for sport, you have to be a proper licensed fishing boat.
Se PROHIBE la pesca deportiva y recreativa de atún rojo

Here's the article with the picture of the boat. I supposed they could have stuck any old boat in the article just to make it look authentic?
Gibraltar acusa a la Guardia Civil de «incursión ilegal» en sus aguas

I am lead to believe the boat was similar to the following

http://www.rodman.es/eng/rodman_fisher_cruiser_870.html

you make it sound like Cuba - whose cigars were banned in the US but were available at highly inflated prices and more sort after than any others.

the GC would appear to have made an illegal incursion into UK/Gib waters, irrespective of the reasons, although they probably believe they were allowed to as they were chasing another vessel.

A Gib vessel should have got in the way of the GC and stopped them from going back out to sea, impounding them. But perhaps that was one of the chess moves that were considered.

If I understand the above correctly it is a Spanish law.I have still not found anything for EU or International law.

The boat was Gibraltar registered with a Gibraltarian crew fishing in International waters. The only so called crime committed was to sail through Gibraltar waters which Spain declares are her's in contraventionof UN Convention on the Law of the Sea 1982

The correct procedure was for the GC to inform Gib of their suspicions, and believe it or not the two authorities do normally co-operate although the recent fishing dispute has put a strain on that.

That would have been a good idea , they could have arrested them for possesion of sect 5 firearms ,braking maritime law , atempted kidnap etc and banged them up for a while , at least until Gib got an apology from Spain.

Spanish fishermen receive some of biggest fines in UK maritime history

Two companies owned by the Vidal family were fined £1.62m in total in a Truro court, after a two-day hearing, in which details emerged of falsified log books, failing to register the transfer of fish between vessels, false readings given for weighing fish at sea, and fiddling of fishing quotas.

http://www.guardian.co.uk/environmen...?newsfeed=true

also at

http://sfpa-ie.access.secure-ssl-ser...r%20290312.doc

Mine's bigger than your's Domino

I got €2.000.000 you only got €23.000

but yours was in cahoots with a British registered vessel - that was owned by a subsidiary of the Spanish Co.
actually I trawled (pun maybe intended) but there don't seem to be many prosecutions of Spanish on the website I found.

Irrespective, I still believe fish cannot see the lines the same way as trawls can discriminate what they catch (yet). taking a ton of mixed fish out of the sea is no good for the environment nor the future of the fish if you dump back 3/4's of it dead because an office wallah has written down figures on a piece of paper....
The oceans are bountious and still a mystery to us, so fish by all means but process what has been caught.
The oceans could be the answer to the future problem of feeding the population of the planet.