Part of a BBC report
Article 227 of Russia's penal code defines piracy as "an attack on a ship at sea or on a river, with the aim of seizing someone else's property, using violence or the threat of violence". It can be punished with a jail term of up to 15 years, depending on the gravity of the offence, and a fine of up to 500,000 roubles (£10,000; $15,000).

The full report
http://www.bbc.co.uk/news/world-europe-24222392

You can decide for your self if they are or are not pirates but it seems the Russians have decided