Manage content items using Views
Create a content view, filter by your gallery content type, add the image field, add the field  "Content: Published" (to let you know if content is published). Then add  "Bulk operations: Content" (you need to install Views Bulk Operations module). In the field settings you should select the option "Publish content" and "Unpublish content". You should now be able to bulk publish and unpublish the image galleries.