He built a fortress on the island in order to close access to the Red Sea and prevent Arab trade with India.
Citation:
Editors. "Socotra seized by Afonso de Albuquerque".
The Literary Encyclopedia. First published 01 March 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=9868, accessed 20 May 2013.]