The reviewer is right. The first sector is a macro conception of agriculture. It indeed includes fishery. However, the data of output and employment are both collected on this level - the first sector. Hence, we assume the quotient of the two variables is a proxy to agriculture labor productivity. Meanwhile, they are the only available data on the prefectural level to calculate agricultural labor productivity. Therefore, we think this calculation is still helpful.
Data issue: The authors indicate their data source as “…an index of panel data on agricultural output and employment in the first sector of 287 prefectures from 2000 to 2010 is collected from the China city Statistical Yearbook (2001-2011)...” It is not clear what kind of index the authors are referring to.