It is likely that Putita stranded whilst hunting stingrays in shallow waters. "It's a very high risk type of prey that they're hunting for, they're in very shallow waters..." Ingrid explains. No where else in the world do orca come so close into shore to hunt for stingrays - they are often seen in less than 1m of water, inside surf zones, estuaries and harbours (www.orcaresearch.org).
http://www.youtube.com/watch?v=5i_mkthGcqg