First of all can i just say you have put together a very interesting site well done! re your question about barracuda you could try spinning with a rapala CD 22 magnum in red & white colour which are usually fairly deadly for the local mediterranian variety of barracuda and also its a very good overall /all round saltwater lure.
Shiny metal spinners work good for them as well,in fact ive heard where big barracuda's are abundant e.g in the carribean,florida etc diving instructors specifically tell people not to wear shiny metal like necklaces & other jewllery!
Halco do a very good range of metal spinners http://www.halcotackle.com/halco_metal.asp
ive done very well with the twisty 55g and the hexagon spinners.
Regarding line i use standard nylon 0.40mm without any wire trace as barracuda's tend to attack from the sides/rear so wire isn't always nessecary when spinning or u could make up the hook length of some heavier mono (?)
Also live baiting works good for them as well,either ledgered off the bottom or fished with a control float a few feet below the surface (depending on depth), however you will need wire trace for this method.The best time locally ive found to catch them is a few hours before and after dawn also the same at dusk.
It may be different in lanzarote though & you definitly can't beat local knowledge/experience so maybe find someone who fish's for them locally who can put you in the know about local conditions/methods.
I have fished for pike with my brother-in-law whilst on holiday in the uk & the 'cuda's are very similar in habits to pike so if you use similar tactics and methods im sure you will be successfull
Hope this post (long! sorry!) helps you to catch one or a few of the them
here is one 1.5kg 'cuda i caught a few weeks back on halco twisty spinner 55g whilst spinning for bonito/bullet tuna
Regards & tight lines,