Fish tracked from DNA 'finprints' left in
waters off New York
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[April 18, 2017]
By Environment Correspondent Alister Doyle
OSLO (Reuters) - Scientists have tracked
fish off New York by following the traces of DNA left in the water, a
technique that could help gauge life in rivers, lakes and the oceans
around the world, a study showed on Wednesday.
Fish leave bits of slimy skin, scales and excretions as they swim around
- clues that let scientists detect 42 different species of fish
including herring, bass and eels in water drawn from the Hudson and East
Rivers off Manhattan, it said.
"Rather than get a big boat and a big net ... we just tied a bucket onto
a rope and threw it into the river," lead author Mark Stoeckle, from New
York's Rockefeller University, told Reuters.
The one-liter (two-pint) samples, costing $50 to process, let scientists
monitor annual migrations of fish in spring 2016 to the rivers and their
estuaries, according to the study published in the journal PLOS One.
It said it was the first time fish migrations had been tracked solely by
Understanding fish migrations can help countries time the opening of
fishing grounds and other activities. In New York, for instance, the
port authority is banned from dredging when winter flounder are in the
By contrast with DNA studies, research vessels using nets to catch fish
to study the variety in an area can cost $10,000 a day. Sonars can also
be used to spot shoals but are less precise in detecting individual
"And the animals may be chased away by the sound of the vessel, or the
pressure of the bow wave," said Jesse Ausubel, a co-author at the
"DNA is opening up the world around us ... we can read the book of
nature just by collecting a cup of water," he told Reuters.
DNA finprinting of fish is similar to genetic fingerprinting of people,
for medical tests or in forensics at crime scenes.
Still, some of the results seemed puzzling.
The study found DNA from exotic Nile tilapia and red snapper that do not
live off New York. That DNA apparently came from sewers after passing
through humans who ate the fish.
[to top of second column]
Researchers sample water from the East River off New York as part of
a study of fish DNA that is helping scientists to track migrations
of species such as herring and bass to the region, in New York,
U.S., October 30, 2015. Mark Stoeckle/Handout via REUTERS
And it is impossible to know if DNA samples came from one fish or
10. Greater sensitivity could pave the way to gauge fish stocks in
Fish DNA lasts perhaps a week in the water before breaking down in
what the scientists called a "Goldilocks" time. Longer would make it
impossible to tell how long the fish had been there, shorter would
make it hard to find any trace of life.
DNA has widening uses for tracking wildlife. A 2008 study measured
wetlands in France to detect American bullfrogs, a species that was
damaging local wildlife after escaping from farms producing frogs'
legs, a local delicacy.
(Reporting By Alister Doyle; Editing by Andrew Heavens)
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