Originally, experts were of the opinion that Nakai's injuries could not have resulted from an orca bite. The U-T San Diego reported:
Dr. Ingrid Visser, a leading orca researcher from New Zealand and anti-captivity activist, concurred with Anderson [veterinarian with the University of California Davis Wildlife Center] that the wound doesn’t appear to be a bite, more like a slice caused by something like a metal plate or a wire. She added that she believed that the injury is more serious than Sea World officials have stated.
“This is clearly a very traumatic wound and it appears to be down to the bone and again, I think that SeaWorld is underplaying the wound,” she wrote in an e-mail. “This is another example of why these animals shouldn’t be in captivity.”
However, new evidence has come to light which now suggests otherwise - that Nakai's injuries arelikely to have resulted from an orca bite.
New photographs of Nakai have been released by orca expert Ingrid Visser, which clearly show four puncture marks at the bottom right of the wound - the spacing matches that for orca teeth as you can see by comparing them to Nakai's teeth in the same photo.
As others have speculated, it is possible that SeaWorld staff members cauterized the wound with lasers to get rid of the rakes before anyone outside of the park saw the injury. But they left those four punctures since they would have had to take too much flesh to remove them.
People for the Ethical Treatment of Animals (PETA) announced on Friday they have filed a complaint with the Department of Agriculture for conditions at SeaWorld San Diego that led to a gaping injury to the lower jaw of an 11-year-old killer whale.
For more information please read the following articles:
Journalist Tim Zimmermann first reported this news -
http://timzimmermann.tumblr.com/post/32433797105/nakaiphoto
'Death at SeaWorld' author David Kirby also investigates the story -
http://www.takepart.com/article/2012/09/28/what-happened-nakai-seaworld-whale-missing-huge-chunk-chin
CBS8 report on Nakai's injuries: http://www.cbs8.com/category/155799/video-landing-page?clipId=7780197&auto
The U-T San Diego interviews Dr. Ingrid Visser about Nakai's wounds -
http://www.utsandiego.com/news/2012/sep/28/killer-whale-injury-down-bone/
CBS8 report on PETA's complaint filed with the US Department of Agriculture:
http://www.cbs8.com/story/19666384/killer-whale-hurt-at-san-diegos-seaworld-show
CBS8 reports on the recent photographs of Nakai's injuries taken by orca expert Ingrid Visser:
http://www.cbs8.com/story/19679464/orca-expert-takes-new-photos-of-killer-whales-injuries
Ingrid Visser speaks with journalist Tim Zimmermann about her professional analysis of Nakai's injuries: http://timzimmermann.tumblr.com/post/32870571126/vissernakaianalysis