vinces99 writes "A mere glass full of water from Monterey Bay Aquarium's 1.2 million-gallon Open Sea tank is all scientists really needed to identify the Pacific Bluefin tuna, dolphinfish and most of the other 13,000 fish swimming there. Researchers also discerned which of the species were most plentiful in the tank. Being able to determine the relative abundance of fish species in a body of water is the next step in possibly using modern DNA identification techniques to census fish in the open ocean, according to Ryan Kelly, University of Washington assistant professor of marine and environmental affairs, and lead author of a paper in the Jan. 15 issue of PLOS ONE. 'It might be unpleasant to think about when going for a swim in the ocean, but the water is a soup of cells shed by what lives there,' Kelly said. Fish shed cells from their skin, damaged tissues and as body wastes. 'Every one of those cells has DNA and if you have the right tools you can tell what species the cell came from. Now we're working to find the relative abundance of each species present,' he said."