If you are interested in this issue, the documentaries Blackfish and The Cove are HIGHLY recommended. 

They were a huge inspiration for Leviathan Project

Blackfish
http://blackfishmovie.com/

The Cove
http://www.thecovemovie.com/
 

Death at SeaWorld by David Kirby
http://deathatseaworld.com/
 

Orca Database
http://theorcaproject.wordpress.com/killer-whale-orca-database/
 

Captive Orcas ‘Dying to Entertain You’ - A report for Whale and Dolphin Conservation Society (WDCS)
http://www.wdcs.org/submissions_bin/orcareport.pdf

THE CASE AGAINST Marine Mammals in Captivity - World Society for the Protection of Animals (WSPA)
http://www.humanesociety.org/assets/pdfs/marine_mammals/case_against_marine_captivity.pdf