Japanese Jack Mackerel (IMAGE) National Institute for Environmental Studies Caption Researchers "counted" Japanese jack mackerel (Trachurus japonicus) in Maizuru Bay, Japan, through quantitative measurements of environmental DNA concentration. Photo credit: Reiji Masuda, Kyoto University. Credit Reiji Masuda Usage Restrictions Credit required. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.