In 1882 Johnston was appointed registrar-general and government statistician. Johnston was appointed a royal commissioner to report on the fisheries of Tasmania, being the author of "Descriptive Catalogue of Tasmanian Fishes" (Hobart, 1882).
In 1882, Johnston was appointed registrar-general and government statistician. Johnston was appointed a royal commissioner to investigate Tasmanian fisheries, authoring "Descriptive Catalogue of Tasmanian Fishes" (Hobart, 1882).