Fish rubbings, 'gyotaku', as a source of historical biodiversity data

Methods for obtaining historical biodiversity information are mostly limited to examining museum specimens or surveying past literature. Such materials are sometimes time limited due to degradation, discarding, or other loss. The Japanese cultural art of 'gyotaku', which means "fish impression" or "fish rubbing" in English, captures accurate images of fish specimens, and has been used by recreational fishermen and artists since the Edo Period (the oldest known 'gyotaku' was made in 1839). 'Gyotaku' images often include distributional information, i.e., locality and sampling date. To determine the extent and usefulness of these data, field and questionnaire surveys targeting leisure fishing and boating stores were conducted in the following regions where threatened or extinct fishing targets exist (four regions including the northernmost to the southernmost regions). As a result, 261 'gyotaku' rubbings were digitally copied with their owners' consents. From these, distributional data were extracted for 218 individuals, which roughly represented regional fish faunas and common fishing targets. The peak number of 'gyotaku' stocked at the surveyed shops was made in 2002, while ones made before 1985 were much fewer. The number of 'gyotaku' rubbings made in recent years shows a recovery trend after 2011-2012. The present study demonstrates the validity of examining 'gyotaku' for historical biodiversity information.