The Sound of LAUGHING FISH!
A few years ago, a friend of ours was wreck diving when all of a
sudden she came face to face with a rather large 'grouper'.
Locked in a fierce stare, the fish started to emit loud grunting
sounds. Surprised by the sounds, our friend grunted back.
Whereupon the fish seemingly decided that it had met its match
and swam meekly away.
We know that cetaceans 'vocalize' - we've all heard the sounds of
the humpback whale singing on prime time TV. But, it's estimated
that perhaps half of all fish species also make sound. I know
fishermen who swear 'the fish were laughing at us'. But,
researchers around the world are just beginning to unravel the
mysteries of fish sounds.
One such researcher is Dr. Joe Luczkovich at the Eastern Carolina
University. He and his team have been working for several years
trying to record and analyze the sounds of fish that live near
the shores of North Carolina's Pamlico Sound.
Using hydrophones (underwater microphones), they 'hunt' for
sounds - identify them - and watch for telltale signs of spawning
activity. For it seems that much of the sound coming from the
North Carolina fish have to do with attracting mates. The male
generates a sound by vibrating his swim bladder to advertise his
presence. And, perhaps, to warn off other males.
One of the problems that Dr. Joe is looking at is the decrease in
the number of various commercial fish species along the North
Carolina coast. Are they being overfished? Are their spawning
grounds being made unuseable by pollution? Or, are boaters and
other human activities unknowingly disturbing the courtship
Tracking fish by their sounds lets these researchers identify
spawning sites. They have found that each species of fish makes
different sounds. So, by listening to the sounds you can find a
spawning area, identify which fish are there and even estimate
their number. If it turns out (as is likely) that fish return to
the same spawning spots year after year, these areas can be
protected by law.
It seems easy, but its not. First, one has to identify the
which sounds are made by what fish. In any body of water that
can be difficult. One of the biggest problems is sorting through
a large amount of un-identifiable sounds. The sea, or even a
pond, can be a very noise place - underwater that is. Back in
1970, it was reported that over 200 species of fishes make some
form of sound. Today, many researchers believe that between 30
and 50 percent of all fish 'vocalize'.
The sounds they make vary. You will hear 'grunts', 'drums',
'doorknocks', 'heartbeats' , 'burps', 'croaks', 'crackles',
'chattering', purring', 'clucking' and even a 'foghorn'!
Try these samples for yourself:
Heartbeat and Burp (126 kB WAVE) - Spotted Seatrout
(Cynoscion nebulosus) Spawning males produce a "heartbeat"
and a "burp" sound by vibrating their swim bladders.
Purring (198 kB, WAVE) - Weakfish (Cynoscion regalis). Sound
made by the drumming of the swim bladders in the males.
Chattering (68 kB, WAVE) - Weakfish (Cynoscion regalis). A
rapid clicking noise. This sound is produced by both males
School sound (160 kB, WAVE) - Weakfish (Cynoscion regalis).
This sounds like static, but it is an aggregation of
spawning weakfish recorded after sunset.
Knocking (189 kB WAVE) - Red Drum (Sciaenops ocellatus) It
sounds like someone knocking on a door. An aggregation of
knocking red drum can sound like galloping horses or even a
Clucking (77 kB, WAVE) - Silver Perch (Bairdiella
chrysoura). This is one of the most common sounds in North
Carolina waters between April and September. Sometimes they
only produce a few short clucks.
Chorus or School (78 kB, WAVE) - Silver Perch (Bairdiella
chrysoura). This is NOT 'static'. It is the produced by an
aggregation of spawning silver perch. "We have recorded this
as loud as 149 dB (re 1 microPa), this is a higher sound
pressure level than a rock concert!"
Fog Horn (840 kB, WAVE) - Oyster Toadfish (Opsanus tau). It
sounds like a foghorn. The crackling you hear in the back-
ground is shrimp. This sound was RECORDED FROM A PIER in
Beaufort, North Carolina
Croak (236 kB) - Atlantic Croaker (Micropogonias undulatus). This is
a croaker alarm call given off by a captive fish in shallow
water in the harbor at Ocracoke, NC.
There is plenty of room for research on your part. Everyday more
species are being recorder and identified. The 'identification'
part isn't easy and the wide scale cooperation and sharing of
sound recordings and observations is needed to help reduce the
enormous task of identifying the 'mystery sounds' of the
underworld. You don't need an ocean, or a boat. Wherever there
are fish there may be strange new sounds to hear.
If you would like to learn more about this work have a look at: