Sound, noises, play a huge part in
human relationships with the world. Our fear filled reaction to
sharp violent sounds, reflects our fear of violence. Aeons of
fear of sharp sounds is etched deep in our genes. For humans things
that go bump in the night are the fuel of fear, .
Despite this we remain fascinated by fear. TV and
film is littered with this fascination. Maybe our fascination
with fear, is some kind of ‘training’. When humans are frightened
they go into a starkly simplistic mode, which selects fight, flight
or submission.
But in the sea, the relationship between predator
and prey is even more simplistic. For the prey the choice is flight,
flight or flight.
For predator fish, the notion of what is noise,
is vastly different from ours. It may well be that noise, commotion,
the unusual, is a key to survival. Predator fish may be forced
to investigate all noise to check whether the noise means food.
How we exploit this concept of noise may determine
our success as fishermen.
Despite this conventional wisdom has it, that quiet
is best when fishing.
There are some fishermen that take extraordinary
measures to reduce noise in a boat. I know more than a few who
will not even allow a radio on the boat, in case the noise is
transmitted through the hull, into the water. A boat hull is basically
a giant drum. Any noise in the boat is quickly, and very efficiently
transferred into the water, where it can travel large distances.
Sound travels much better, and further, in water
than air. Those who dive will be aware, of how loud the noise
of a passing boat can be. Divers who have been lucky enough to
dive near dolphins or whales will know sensation of both the sound
of their ‘calls’, and the tingling feel of their sonar signals.
Many years ago I worked briefly on a prawn boat
out of Coolangatta in northern New South Wales. We had the benefit
of sophisticated sonar equipment. But when the prawns rose off
the bottom at night the sonar would immediately go into a spasm.
The ‘noise’ made by millions of legs and tails scraping together,
blew the signal processing software inside the sonar apart. It
was not until we turned down the discrimination knobs up to nearly
off the scale, which meant only one signal in thousands was being
processed, could we get an accurate depth reading of the prawns.
Some skippers swore that you could hear the noise
of prawn schools through steel hulls, and even better through
aluminium hulls.
Until the prawns rose from the bottom, the sea bed
would often be lifeless. No signs of fish. But in a very short
after a prawn school rose, the sonar screen around it would be
splattered with fish.
I enjoy fishing estuaries on a quiet, still night.
Drifting slowly along, pushed by the incoming tide, picking up
a few fish with a drifting bait, is a quiet pleasure.
Well I thought it was quiet until I heard a recording
of the underwater noise as the water covered the tidal flats.
Down there it is a constant cacophony of sound. The scraping of
crabs legs, is as clear and sharp as the scream of chalk on a
blackboard. The sounds of empty shells being rolled along the
bottom by the incoming tide, was like Jaffas rolled down the cinema
floor from the back rows.
The recording equipment could convert pressure waves
into ‘sounds’ audible to the human ear. We could plainly here
the whoosh of shellfish expelling water.
Is fishermen’s noise a problem when fishing? For
me the jury is still out.
Here are three pieces in the noise puzzle.
The first piece concerns young Ed the lad. During
the early teen years Ed was downright clumsy. I put it down to
the fact that his body was growing so fast, his nervous system
could not catch up. Messages were taking too long to travel from
his brain to his limbs.
Fishing in the tiny tinny, Ed set new levels of
noise pollution for the surrounding area. Once I swear I saw the
periscope of a submarine pop up to investigate the noise that
had shut down it’s sonar system. Maybe they thought a small war
had broken out.
When we reached a fishing spot, the normal course
of noisy events was well rehearsed.
Ed would pick up the anchor and chain, and promptly
drop it on the bottom of the boat. He would pick it up again,
and toss it over the side, allowing the chain to bounce and rattle
off the front coming.
Then Ed would pick up the tackle box, drop it, pick
it up again, and drop it onto the aluminium side seats. Rigging
up became the signal to drop sinkers and knives onto the bottom
of the boat.
Only those who have fished from tinnys know the
extraordinary ability of these boats to transmit sound.
Eventually Ed would fire out a bait, into water
still rippling with the sonic aftermath of all this noise. Often,
too often for the conventional rule of being quiet in a boat to
be universally true, he would immediately hook up.
The second piece of the noise puzzle is provided
by Mark Kitteridge who works with me at the shop. When the boat
reaches ‘the spot’ you would have to move at the speed of light
to get a bait or jig into the water ahead of Mr. Kitteridge. The
anchor crashes down, and so does Mark’s bait, almost simultaneously.
Too often for other fishermen’s egos, Mark hooks up almost immediately.
The third piece is provided by a number of good
and better kingi fishermen. These guys motor up to the spot at
full throttle, and then execute a series of figure eights in the
general area. One of these blokes has a bag full of hard stones.
As soon as the boat stops he dangles the bag over the side, and
vigorously shakes it up and down. Divers chasing kingis used to
bang a knife on their dive tanks to attract kingis. The clanking
noise of the hard stones is similar.
The noise and commotion attracts kingis around too
often for it to be a case of the kingis arriving despite the noise.
Also, and again, happening too often to ignore,
is the number of big snapper that grab a live bait intended for
kingis, amongst all the noise and commotion.
On the very rare occasions that I have been able
to see snapper in a berley trail, I have been fascinated that
every time a fish is hooked up, the other fish get excited, and
dash about grabbing everything in the water.
It seems as if the struggles, the ‘noise’, of the
hooked fish are read as just that, the struggles of a wounded
fish. There appears to be no kinship amongst fish. The fact that
it is another snapper that is in trouble, does not seem to deter
its kin. A struggling fish, any fish, friend or foe, seems to
spell food.
More often I have seen Kingis in the burly trail
totally uninterested in a live bait which is in their and my plain
sight. Throw a popper in the water, and stir things up a bit,
and off goes the livebait. Sometimes a rod tip slashed through
the water in figure eights does the same trick.
The problem of kingis being uninterested in a live
bait, seems to be more pronounced, if the live bait has been in
the water for some time, before the kingis turned up. Throw a
fresh live bait into the water, after the kingis turn up, and
the bait boredom factor is much less in evidence.
It is my guess that the first signal to a predator
that a food fish is in trouble, is the unusual frantic ‘noise’
of its movements.
The violence of panic, signals the ultimate act
of violence.
By human standards fish are deaf, at least, they
‘hear’ sounds in a different way to the human ear.
The most responsive sense for a fish is not sight,
or smell, it is ‘feel’. But again it is not ‘feel’ in the human
sense. Down each side of a fishes body is a line of receptors
that can detect amazingly low levels of sonic, and other pressure
wave, disturbances in the water. These receptors can detect pressure
waves caused by other fish swimming, sound waves, and other underwater
disturbances.
In predator fish the ability to detect this underwater
noise, and locate the source, is a prime factor in successful
food detection. This ‘noise’ is ‘heard’ long before any smell,
or sight, of food is picked up.
It may well be that predator fish find the bulk
of their food by homing in on ‘sounds’ that indicate disturbances.
These ‘sounds’ may be the frantic movements of bait fish being
harried by other predator fish. Noise, as we know it, may be an
ally, rather than an enemy.
To paraphrase Dr McCoy, on the Starship Enterprise,
“It’s noise Jim, but not as we know it.”