SharePoint 2010 Site Collection Access

I have a minor problem which nevertheless requires some smarts to approach in a time efficient manner. In a given SharePoint 2010 Farm one power user has created a number of site collections (>50) containing important information. No one else has access. I need to go through and:

1. Identify which site collections this power user owns.


2. Assign ownership or full control to another existing user.

Is there a quick way to do this or is it just going to be through hard slog?