Did the Emperor of Japan really write a paper?
According to the Indian embassy of Japan he did author a similarily titled paper in 2008: link (titled Evolution of Pacific Ocean and the Sea of Japan populations of the
gobiid species, Pterogobius elapoides 
and Pterogobius zonoleucus, based on
molecular and morphological analysis), so it is a safe bet that the paper you are asking about is authored by His Majesty as well.

The Internet also confirms he specializes in ichtyological research.