For a year I spear extensively in La palma waters, and freedive Gran Canaria, la Gomera and Fuerteventura...
Those islands are in open ocean, and in many sectors fish populations are healthy and full of surprises. One of then was a distracted 18 pound snapper eating a octopus
. Grouper kingfish, red snapper and many more.
The water is cold (5mm is enough), generally clear with days of perfect viz. Waves can be barbaric and more than once I've encounter unexpected and strong currents at familiar spots.
On the sad side, the fisherman's are depleting the coast: they use explosives, huge fish traps (is not uncommon to see some of those lost and that keep killing fish for years), long lines... As result you have areas the call "blanquizal" where the black urchin population gets out of control and clean white all the rock surface... a real underwater desert.
The have a lot of "botelleros": tank divers that do good money supplying fish to the restaurants. Those are the main cause fisherman's hate anything holding a gun.
At the time I was living up there, YF Tuna and sailfish where plentiful with a tag price at the fish market of what would be now 3 Euros the Kg. Since a friend running a charter big game fishing boat as close down... lack of fish!
The best diving place on the islands would be El Hierro, where the fishing is better planed and the sea ecosystem seem to maintain some balance. But all the islands are an amazing place well worth the trip, and I highly recommend it to any one... Maybe avoid the massive touristic areas, unless you hunt for another kind of game :inlove
Did I say that the señoritas can be breathtakingly pretty?