prevent full membership list from displaying

on site: lymanboa.com/cms30/index.php running CB 2.0.14, we have a Member Search list, but if nothing is entered the full list of members displays, but the client would like to prevent that.
they want members to be able to search, but for the list to only show members that fit the search criteria.
Is there a way to do this?

thanks.

Edit the list -> tab Parameters -> tab Search -> option Hide Empty Searches = Yes.