Fish leave behind telltale DNA fragments that can be sequenced directly out of seawater.
Sampling DNA from seawater may be one way to check up on ocean life, according to research.
And it appears that the relative amount of DNA found in an aea for a specific species closely matches actual abundance of the fish.
So we can get an idea of the abundance of a aquatic species simply by sequencing seawater.
Image: NOAA Photo Library