David Prosser at Jisc blogs on the need for action on discoverability

… 40% of researchers kicked off their project with a trawl through the Internet for material, while only 2% preferred to make a visit to a physical library space. [yet] nearly half of all items within digitised collections are not discoverable via major search engines by their name or title [and, even worse] digitised collections become harder and harder to find over time, for a variety of complex reasons.