Danish scientists say they have developed a process to detect the presence of fish and whales in local waters through the DNA analysis of water samples, an innovation that will help researchers more safely monitor biodiversity in the world’s oceans. Using sophisticated DNA sequencing technology, researchers from the University of Copenhagen say they were able to detect DNA from 15 different fish species from a half-liter sample of seawater. According to Philip Francis Thomsen, one of the authors of the study published in the journal PLoS ONE, tests of the water revealed the presence of small and large fish — including common species and species rarely or never recorded by conventional monitoring — in the waters off Denmark. “Cod, herring, eel, plaice, pilchard and many more have all left a DNA trace in the seawater,” he said. The researchers say the use of DNA technology may offer a less invasive way of monitoring marine populations than traditional methods, such as the use of trawls and pots. In addition, such DNA tests could be conducted almost anywhere and on any species, unlike typical monitoring methods that focus mostly on commercial fish species.