The Swarte Beer

The Monnikendam Directors' ship Swarte Beer served through the First Anglo-Dutch War. We know the armament on 21 June 1653, from an inventory. The ship had 2-18pdr guns, some 12pdr guns, with the main battery being 8pdr guns. The Swarte Beer also had some 4pdr guns and 2-3pdr guns. I have wondered about the widespread use of 2-3pdr guns by many ships and have not heard a good explanation of how they were used.