The population data was obtained from 2020 population census of Japan (). The total agglomeration was calculated as the coastal cities closest to samples area. Distance from river was calculated using the "measure" tool in Google Earth (Version 9.178.0.1 ). Salinity, chlorophyl and depth were all taken from CTD records after tows and sediment collection and rainfall data was taken from Japan Meteorological Agency (). Fishery and aquaculture data was collected from Ministry of Agriculture, Forestry and Fisheries Census and Statistics Office, 2018 census of fishery and statistical survey on marine fisher production (). Maps were produced with the QGIS software (), base map of Japan was obtained from the Japanese Ministry of Land and Infrastructure ().