Are all abbots surnamed Shi?

Generally speaking, yes. The origin of Shi surname is as follows: when Buddhism was first introduced to China, foreign monks took the country name and ethnic name as their initials; Han monks use common surnames or teacher surnames. Until the Eastern Jin Dynasty, it was believed that Buddha took Sakyamuni as his surname, so monks should also take Buddha as their surname, that is,' Shi' as their surname. Since then, it has become a practice for monks to take teachers as their surnames. For example, biographies of eminent monks in Liang, Tang, Song and Ming Dynasties, as well as Japanese books such as Yuan Heng's Interpretation of Books and Biography of Eminent Monks in this dynasty, all take the surname of eminent monks as the crown. Later, stone became the general name of monks and nuns, and gradually extended to Buddhism or Buddhists.