Thank you guys.
The fish stock is far more affected by industiral fishing then by spearfishing so I highly doubt that the ban on spearfishing has any relevance. Bulgaria, the neighbouring country from the south, doesn't ban the spearfishing and one cannot notice any differences in the fauna when diving north or south of the border.
As for gear I'm currently using Mares Sten pneumatic spearguns and Omer Stingray palms.