View Full Version : Sound in water

10-08-2002, 10:11 AM
I was at a club meeting in Perth the other night and there was some comment about noise in water from boat traffic and the differences in electrics etc.
Well all cities close to the ocean introduce a high noise level into the ocean, and particularly into river systems, like the Swan.
Most cities have very high noise levels, in the underlying earth, due to trains, traffic, manufacturing, power generation etc, and it can be very high in real terms. Fish in river systems like the Swan live in the ambient noise level and any boat traffivc noise has to override that ambient noise before it becomes obvious. But boat traffic doesn't only introduce noises associated with engine types but there is cavitation noises from properrors as well and this is usually around 10/12Khz depending on the type of prop.
Submarines and warships have specially designed props to reduce cavitation.
But generally speaking fishes in the open ocean might be more intolerant to boat noises, engine types and cavitation than those fishes in, say the Swan River system, or and harbour or estuary system near a large town or city, Cities like Wollongong and Newcastly which have a large steel works could be very noisy.
Its very interesting and maybe the local fishing interests could pop this in front of the Local University to do a bit of research on introduced noise due to the city environment and the levels of ambient noise.
There might be some books on the subject, or papers, in University Libraries for interested parties. Cheers have fun Max

10-08-2002, 05:09 PM
interesting topic Max.. :).
It would be interesting it find out how much of an effect noise pollution in a water way has on Marine life...
A while back while they where knocking in new pylon for the wharf here in Cairns I refuse to fish the general area due to the noise pollution and the firm belief that it deter fish..
Fish to an extent could be somewhat like us. Some frequencies tend to be very sensitive to our ears and can be very annoying ( High pitched), while other frequencies pass as light back ground noise with not much bother..
Intensity of this ambiant noise is another factor.
It is the firm belief by many that marlin are attracted to certian motor noises, and prop noise...with diesel engine being better , i think...Can anyone else confirm this.
Hearing of fish being very different with some bony fish species of herring having extremely high frequency hearing,sounders will put down schools of these fish, and the herring use it to avoid dolphins/whales.
interesting fact about dolphins and certain whales is that their teeth are placed i think 180 degrees off centre from each other Left vs right, that way as vibration travel through water and pass through the bony teeth , the dolphin can use this information a bit like a stereo pickup to tell the direction, and give clearer reading of sonics.
Most fish generally have very good low frequency hearing not only through their otoliths , but also by means of their lateral line.
I firm believe that like a human that can tell when car is out of tune by the way it sound , fish also use this keen sense to tell when other fish are out of tune,sick or injuried.
The other day i hook this small barracuda, not long after i had about 15 mangrove jacks surrounding him ,and following it around, they could tell that something was not right.
Barra are another fish that respond well to sound ...
The study of lure frequencies would be an interesting one, to see if aspecific frequency , sonic footprint was more productive.
Think about it juvnile fish frequently school up , the movement of their tails (frequency) also tend to be higher than adult fish, it still very low for us , but i remember noticing that cycle rate may well falling in to the low frequency hearing of predatory fish....Now what is the sound of a thousand sardines beating their tails, Surely there must be some noise created.....or do they swim out of phase from each other to cancel the noise....?

There's a lot of interesting thing to consider..


10-08-2002, 09:34 PM
Well I tried to find out if any acoustic research had been done in the swan and the immediate coastal area but it seems that no-one knows and the answer is generally no. Funnily enough I could actually set up my old system, using a very old but pretty good hydrophone sysytem ex a sonobuoy. Still there are a large number of papers on sound transmission in water, specifically the ocean and things have been done on porpoises and whales. I have a number to ring on monday, might get some answers. Qld Univ might know something, it might be associated with Brissy and the river. Cheers Max

11-08-2002, 04:16 AM
With the fact that sound travels faster in water will that also effect the pitch frequency , meaning that it will actually sound an octave or so higher...?

Max if you find out any info from the uni's be sure to post it up I would be very interestyed in it.

I wonder in fish can suffer hearing loss..?


13-08-2002, 09:17 PM
Intriguing topic Max, and a couple of questions to toss into the mix

If "noisy water" fish are more tolerant of noise, would this be achieved by lowering their sensitivity to all sound, or by raising it for specific freq etc.

In the former case would this mean fish using sound less as a hunting tool and if so what other senses might become more dominant- eyesight?

Would flies with rattles etc be less effective in these types of environments or more.

Be interested in checking this thread out for future developments.

13-08-2002, 09:49 PM
It's interesting but I guess one really can't make any statements without having some idea of the ambient sound level and the sound spectrum.
I guess it isn't very high, in db's since fish are stll there, mostly, and probably a lot of attenuation is involved in getting it from the strata, like mud sand etc into the water because the strata/water interface presents a sort of wall, or have a reflection coeffecient. In other words only some gets past the interface.
On the other side of it, fish have to have sensitive hearing, and their lateral line is pretty sensitive to low pressure variations. I guess they just live with it, and maybe since some are spawned in that water, their sound sensing might be effected in some way.
The problem is, around Perth anyway, no-one seems to have done any measuring, or see any need to do any, its really noise pollution after all.
The other problem is that the velocity of sound is relative to the medium, water/rock/compacted sand etc so how the frequency would be effected is a sort of mystery. But near bridges, rail motor transport etc, the sound travels into the concrete piers and then into the water. It might be high around bridges and little fish might use that noise to mask their own pressure variations. It doesn't seem to effect barnacles etc. Max

14-08-2002, 03:05 PM
I am in the process of recording some toe tapping music to pipe through the local waterways in an attempt to encourage the fish to take the flies and get excited.I was thinking of some fishing related tunes such as "you took the worms outta my mouth","prawn to be wild", "body and sole","bream there done that",hold the line","hooked on a feelin","for your flys only","you can leave your sprat on","prawn in the USA" to name a few,anyone else got some I can try.Will be fitting the subbies and woofers next week to the boat and am thinking of maybe adding some effects like mirror balls and pyro technics! :D :Dhttp://www.ausfish.com.au/chat/images/smilies/cwm32.gif :D

14-08-2002, 04:40 PM
Sydfly the mirror balls really are not a bad idea..
Divers use them as pelagic attraction devices, they anchor floating mirror balls at various length off the bottom , and then set up a ambush for fish, they work well for mackeral.
I though of making a portable fad like this to attract macks in, while I cast flies at it...


15-08-2002, 11:37 AM
I expected some drivel on this subject, marvellous ain't it, right on cue. Max

15-08-2002, 07:47 PM
Hi Max,dont take it so seriously.It was not so long ago you were talking about fishing shows lacking a bit of humour.I was only trying to add a bit of light heartedness to the topic.
I think fishing should be fun and enjoyable and less of a fact finding pissing contest.Even the technical side of the sport can be fun and enjoyable.The minute it looses the fun it becomes a bit tragic.I was not in any way demeaning your thoughts on this interesting topic,i was merely trying to open its appeal to more than a handful of blokes with waterproof db meters!.If that means adding a bit of humour,so be it!!!!
I half expected you to join in and have a bit of a laugh along, but maybe that asked too much!
Hope that I can achieve your amount of experience as years go by but maintain my own sense of humour(no matter how bad!!!!!!!),lifes to short and fishing aint a chore! ;)

15-08-2002, 07:54 PM
Hey Steve,I think I remember a previous post of yours on mirror ball FADs.I dont know exactly but I believe they are very expensive to buy.Saw a guy at a club climb on someones shoulders and knock one down to the ground once.Was told it was over $1000 to replace.They would work well I guess, like dozens of little witch doctors.Not sure if they are that useful over here but will look out for cheap ones(probably easy to make),cheers, Justin. :)

16-08-2002, 03:01 PM
Justin one of the local guys up here was telling me how he found these cheap small mirror balls in a "Crazy Clarks' type store , they where about 5 buck each...that price sound good to me.
After jumping overboard with the mask and snorkel, he reckons the way the mirror ball shines little beams of light every underwater is amazing and it isn't hard to see why it attract pelagics towards it .
i definately wouldn't be investing 1000 hard ones for a big disco FAD.

Steve Ooi

18-08-2002, 12:04 AM
There are a number of little tricks that the old timers used. Like putting mirror strips under their boats to drag Kings up, and shiny mirror teasers. I used a very big hunk of a big aluminium type balloon. It just sat in the prop wash and flashed. Pulled marlin right up to it and nothing would get them off it, until they just dived under it and took off.
I've got a sense of humour, but its kind of stretched lately, seen too many needles etc. Max

18-08-2002, 06:12 AM
Fair enough,hope i never have to go through it!

18-08-2002, 04:34 PM
Well 30% of people who have heart attacks do not know they had them. They are dead before they realise what happened. But try this

The information obtained by such method can supplement the information that can not be yielded by the passive listening method. In addition, another direct implication of this research method is the understanding of how man-made sound such as boat engine noise can impact overall change of hearing ability of fish. Hong Young Yan’s laboratory has demonstrated that exposure to high intensity noise as short as 2 hours can alter hearing ability of some fishes and the recovery of hearing ability takes up to 5-7 days to return to normal.

Interesting, called noise pollution, and is related to the ambient noise from man made sources, like big cities, big industries etc. Max

18-08-2002, 06:29 PM
I haven't come across much on fish being affected by noise-pollution. I do however, remember seeing a documentary on an Asian River Dolphin species (perhaps in the Yankzee River?) that was endangered and in danger of becoming extinct because it was having trouble navigating with all the ambient background noise. I think they were turning up dead a lot struck by boats, as although they could under normal conditions avoid boats, with all the ambient niose (noise pollution) they could no longer avoid them. You mightn't want to quote me on this though, I'm just drawing on strings of memory here!

I guess that brings into the equation their ability to hunt as well. I suppose this applies to other fish, especially those who are attracted to and use vibrations in the water to hunt.

Interesting to see if there is any definitive research in the area. I suspect large scale research on this would be confounded by a million other influencing impacts, and it would be difficult to separate the effects of noise pollution from other forms of pollution and fishing etc.


20-08-2002, 02:42 PM
Well I guess in the Yangtzee which is mostly mud a dolphin would rely on sound to find anything at all and a high level of ambient noise would simple stuff him up.
But so far no-one that I can trace has looked at the Swan River noise levels, nor any other place on our coastline, Melbourne Port Phillip Bay, Sydney and the Harbour, Newcastle whatever. Seems strange in this day and age. But its just a query, I don't have time to go around dipping hydrophones, even it I wanted to. Max