Fish Sounds: Do fish talk to each other? | The Travel Edit

whenever i tell people that fish have
ears they look at me like i'm mad
but not only that people are surprised
by the really unusual sounds that fish
can make
and especially on a coral reef
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when we're listening to a reef we hear
the the snapping shrimp crackling away
and then as we add in chirping perhaps
of some fish that are trying to impress
a female on on a nesting site
and then we've got the clownfish that
are using sounds to communicate within a
colony and particularly to warn each
other of a predator
these are fish and invertebrates that
are making sound for a range of
different reasons they're sometimes
trying to find prey and they might be
hunting together so they're actually
talking to each other while they do this
they might be trying to detect predators
obviously they want to avoid any
predators
but they're also then using sound to
establish a territory to impress each
other
so it's a bit like listening to a full
orchestra and it produces this wonderful
cacophony of biological sound
and it's recent advances in technology
that are allowing us to better
understand this communication
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a hydrophone is a device that allows us
to listen underwater much better than
our ears would work and also to record
this sound
with these hydrophones up till about
1960 or 1970
were generally used by the navy and they
are primarily used to listen out for
submarines and to listen out for
torpedoes
so nowadays hydrophones are much more
readily available off the shelf which
means that people are gathering really
valuable recordings from around the
world and we're building a global
understanding of the soundscapes in the
ocean
and one of the more recent and really
exciting developments with hydrophone
technology has been alongside wildlife
film filmmaking the rig that we used on
ocean's our blue planet is made up of an
array of hydrophones and with four of
these we can now listen in four
different directions at the same time
so what this does is it gives the
the viewer a stereo feel of being under
water or even a surround sound feel of
being under water
but as biologists what we can then do is
to look at where individual sounds are
coming from
and the way we do this
is to look at the time of arrival of a
sound
sound travels very fast underwater and
with this array of hydrophones we can
look at whether one sound is just a
millisecond behind in one of the
recordings
then when we add the video
it then allows us to work out which fish
is making which sound
although it was really innovative for
filmmaking we found that it's now
helping us to unlock a whole new
dimension of underwater sound with our
science
we're only just beginning to understand
these natural soundscapes with our
hydrophone technology but sadly we're
also realizing there are many unnatural
sounds that are now making it difficult
for fish to communicate
more recently we've realized that human
noise is part of that modern
contemporary soundscape
so pretty much everything from a blue
whale to a plankton shrimp is affected
by human noise
now this human noise comes from lots of
different sources
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so some of it is through different types
of vessels
there is also the sound from seismic
surveys looking for oil and gas where
huge underwater explosions create noise
that penetrates kilometers into the
seabed
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or from construction a lot of that
construction noise can be pile driving
so that's banging very large steel piles
into the seabed so all of these sounds
now are
producing an acoustic fog over our
natural soundscapes that we know are so
important to animals
so that at the very least is likely to
affect communication
we also know now that human noise causes
stress in animals and so this can affect
early development some eggs don't hatch
some eggs hatch but are malformed and
this acoustic stress has caused changes
in early development
but also that sound through stress can
then affect the ability of a fish to
respond against a predator so we see
fish
more vulnerable to predation when
motorboats are driving around as an
example
so we're building this awareness of how
sound can affect
all sorts of marine animals
the
exciting thing that we found is that
actually these these noise producing
industries have been very willing to be
part of the science
in that they are actually very
interested in a range of ways of
reducing the sound that they produce so
sound is one of the pollutants that
we've got the most control over we can
really fix things very easily and that
kind of gives me a lot of hope
particularly working with industry that
it's the pollutant that we'll fix in our
generation possibly in the next 10 or 20
years
the more we study underwater acoustics
the more we're realizing that technology
like our hydrophone array are allowing
us to unlock the behavior of fish but
also to measure the health of the ocean
but we've still only just scratched the
surface
what else will we find by listening to
the ocean
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