If you don’t fancy being eaten by a Great White, then this might ease your anxiety.

>>Whether it’s in sloughed skin, feces or other biological substances, animals regularly cast off bits of their DNA into aquatic environments. Known as environmental DNA (eDNA), it can be detected in water samples, letting scientists know if a given species is present in the region. Soon, it could be used to warn beachgoers of nearby great white sharks.<<

https://newatlas.com/edna-great-white-sharks/56349/

PermeateFree said:

If you don’t fancy being eaten by a Great White, then this might ease your anxiety.

>>Whether it’s in sloughed skin, feces or other biological substances, animals regularly cast off bits of their DNA into aquatic environments. Known as environmental DNA (eDNA), it can be detected in water samples, letting scientists know if a given species is present in the region. Soon, it could be used to warn beachgoers of nearby great white sharks.<<

https://newatlas.com/edna-great-white-sharks/56349/

> mitochondrial cytochrome B gene

Yes, that’s the way to do it. Mitochndrial DNA is present in much larger quantinies than all other environmental DNA, and cytochome DNA is highly conserved within species and differs just enough between species to be interesting.