Topic: Can fish hear sonar?

[werethefugowee]

I've got a 997cSI w/downimaging, and have had it for a long time. Almost 3 years. Love this thing.

My question is about any sounds emitted by my unit that may be heard or felt by fish. For example, catfish have lateral lines all over just like sharks. This is how they know what is going on around them.

If I am sitting still or close to it and not concerned about what is under or around my boat - should I shut it off, change frequency's, anything?

This has been an ongoing argument/discussion between me and my buddy. I say NO, and he says YES.

Anyone have an opinion on this?

Thanks in advance for any and all opinions.

 

[ITGEEK]

Well,
Here's my 2 cents.

Sound travels through water 5 times faster than in air.
Sonar pings are not a natural sound in the fish's environment.
I guarantee all the fish can hear/feel them.

In high pressured lakes, some fish probably know that sonar sound means danger.
Some may get used to it and not be affected, but all the fish are probably aware that something
unnatural is in their environment.

Now, as far as Catfish, I target big Blues myself.
My opinion about Catfish is that once they get pretty big, say 15 pounds, then they don't
have any natural enemies..  I don't think they scare easily or are too afraid of what may
be around them.  I think they have a one track mind, to find food.

Some people use Flurocarbon leader to make it invisible to Catfish.  Based on my experience, I strongly believe that you could tie a piece of bloody bait to a chain link and the Catfish won't care, they'll still bite it.

For Catfishing, I doubt that the sonar pings will spook them.
But, if your goal is to be as quiet as possible when fishing, then yes I think you should turn off your sonar once you get to your fishing spot.

[Roddy]

Yes fish do hear sound by way of the Idolise in the skull.

I have a, sound Hydra speaker and play sounds of fish feeding when fishing, It works!! Here fishy, fishy,fishy, bite the hook!!!

[werethefugowee]

Wow! Well, that is another argument/discussion that I've lost.

At the same time it brings up a new fishing strategy. Use the sonar to find my projected "here is a good place to drift thru" - unplug the transducer - and follow thru with the GPS track in the same place.

Fishing just got more complicated.

But I did learn something. Thanks for the information.

[ITGEEK]

Well,
You really haven't lost the argument/discussion.
I'm sure everyone has an opinion of how much the sonar will actually
affect the fish.  It probably has different affects on different species.

Here's another strategy.

Go through the area you plan to fish first with the sonar on.
Then, GPS (make waypoints), of any locations you see fish in.
Then, turn off your sonar, but keep your GPS on.
Wait 10 to 15 minutes for the fish to settle down.

Then go back and fish your spots using the GPS waypoints.
No sound will enter the water if you have your sonar off.
Except the sound of your propeller.
To be really quiet, use your motor sparingly.

Good Luck.

[werethefugowee]

ITGEEK that's what I was trying to say. I catfish and troll for Walleye. I've always had it on all the time and now I know when to turn it off. Thanks.

Like I said before - a whole new strategy and understanding.

Maybe this is why my catfishing could use some improvement.

[Roddy]

I never turn any of the six (6) Units off that are mounted on my boat and land fish always. From what I understand it is a Volume/Freq/Pitch and fish v Mammel brain size thing.

The underwater world is a very noisy place.

Roddy

[Humminbird_Greg]

According to some of the experts the frequencies used by sonar are outside of the hearing range of fish.  Much like those high frequency sounds that only dogs can hear but we cannot (or whatever frequency my Wife uses when speaking to me…).  I think that the fish would be more spooked by this large dark object that is floating by over their heads…

[sonar2000]

It may not be the exact sound but more the virbration of the sound. Fish are very sensitive to any surrounding change..
Chuck

[werethefugowee]

Thanks  go out to everyone for the input.

So, Yes fish do notice the sonar, some species more than others, busy waters = lots of noise and the fish are not as spooked as in quiet waters where they are not used to it.

Learning

[Doc Stressor]

What you have here are a bunch of opinions that aren't based on real facts.

The acoustic sensitivity of about 100 different species of fish have been pretty well studied. Most can't detect sound above about 1 kHz. Since most transducers put out and detect frequencies of 50 kHz and higher, fish can't hear the signals.

Here is a good review of the recent literature if anyone really wants to get into this topic:

http://afasteis.gcsaic.com/docs/Effects%20of%20Mid-%20and%20High-Frequency%20Sonars%20on%20Fish%20by%20A.%20N.%20Popper.pdf

[werethefugowee]

Doc, thanks for the link. I read a little of it and saved it. Will go thru it completely in the morning.

Again, Thanks.

[mendota]

The "click" of a sonar pulse has frequency content from near DC all the way up to the nominal output frequency.

That's why both you and the fish can hear it.

The article applies to continuous-wave sound, which sonar is NOT.

[ITGEEK]

If a fish can use it's lateral line to find prey in the dark, I would think it
would be able to pick up unnatural sounds/vibrations in it's environment.
This would no doubt help it survive better.

I don't need a scientist to tell me that fish can sense my sonar pulses.
It's just common sense.
If I can hear it in my garage (out of water), I know damn sure the fish
can hear or feel it in the water.

[sonar2000]

I think the use of the word "hear" is definitive.  Hear, as we the human hear, is different to a fish is we are to use the common word.
To a fish,it may be the detection of particle movement by the air in the bladder and then relayed to the inner ear.

We may be to much into the rocket scientist area here as the question really is....Can fish detect sonar and if so how does that effect their behavior.

This is to mostly, a new frontier, and maybe deserves some  attention.

So to you guys that fish by sonar we can ask.....
Do you see on your sonar effects on fish of having sonar introduced into their habitat?
Maybe something like ...... can you see fish change levels or position when sonar is applied initially. 

If fishing is slow then lets research the effects of yes or no on fish detecting sonar..

This sounds like a project for Roddy.....

Chuck 

[xSilmarilSx]

I can say for sure, that aquarium fish are spooked by the size of the transducer. Turning the sonar on/off don't change anything in their swimming patterns!

[Doc Stressor]

We hear the transducer click because a tiny amount of the transmission burst is outside of the nominal frequency range. As mammals, we can easily hear sounds in the 10 mHz range and even higher frequencies when we are younger. Even the few species of fish that can hear up to 1 mHz have very low sensitivity to sound near that limit.

The crystals used in fishfinder transducers are constructed to emit sound at very defined frequencies. The standard is +/- 2 mHz from the central frequency. The intensity of any sound that is emitted within the hearing range of fish is well below their sensitivity threshold.

Fish detect sounds through their internal ear bones, which are often articulated with the swim bladder. The lateral line is used to detect changes in pressure, which is measured at frequencies well below those that can be detected by the ears. When a moving object approaches a fish, the pressure change is detected though the lateral line. This isn't a sound in the usual sense.

Putting scientific studies aside, I have fished with sonar since the early 1970's. Some of that was commercial fishing for grouper, where even minor factors are very important the outcome of a trip. Turning the sonar on or off has never had an effect on the bite.  To this day, anchoring over shallow reefs where I can observe the fish, I have never noticed any change in behavior when the sonar is switched on or off. Turning the battery switch off can have an amazing effect if you have a current leak, but the sonar does nothing to fish activity.

[ITGEEK]

Doc, So,
You have caught fish with the sonar on and with the sonar off.
I'm sure that many people have caught fish with the sonar on.
That doesn't mean that there is no affect on the fish.
No one can say for sure what the affect might be.

Maybe the fish you are fishing for have had thousands of boats over
them using sonar and they have been conditioned to it.
Maybe it's the younger fish you are catching and aren't as wary as
the older fish.
Also, maybe you are fishing really deep where the sound is dissapated.
There can be a hundred maybe's.

Let me ask all of you a question:
If some scientist claimed that sharks can't hear sounds within a certain range.
And another person created a shark attractant device.
The inventor claims the device pings like a sonar and attracts sharks, but in a range the other scientist says sharks can't hear.

Would you go swimming with the device attached to you?
I wouldn't.

[Doc Stressor]

The way to think about the problem is to use the scientific method.

Try to disprove the null hypothesis: Fishfinder sonar has no effect on fish behavior.

Does anybody have real evidence that it does effect fish behavior?

[ITGEEK]

That evidence would take lots of time and lots of money to obtain.
Probably years of study in controlled environments to see how much
affect, and what exactly is affected.

Does anybody have any real evidence that it does not affect fish behavior?
Just because a fish bites with the sonar on doesn't mean they are not aware of
the sonar.  They may be a little more cautious with it on.

They may be so hungry that they throw caution to the wind.

I think the fact that a fish knows something unnatural is in their environment
would be enough to turn some fish off.

I guess all we ever will have on this is opinions, and not hard facts.
If I wanted to be ultra-stealthy, I'd leave the sonar off.

[werethefugowee]

I started this topic wondering if fish could hear my sonar. Now I feel that it is actually more of a "feel" than hear.

Some background on why I asked. One of the places that I fish is where the Castor River runs into the Mississippi. It's called the Diversion channel down there and was "channelized" to help drain the bottom land. Almost no current, maybe 1/4 mph. I have a pontoon boat and like to slowly drift fish for catfish. Nothing turned on except the 997. I've noticed that on calm days as I drift that there are small bubbles coming up behind the boat. Go to the front and no bubbles. The water is 10 to 20' deep and has lots of decaying everything that washes down the river.
                   
 After I noticed this several different times I began to think maybe it was my sidescan.

And here I am.

I do appreciate all the discussion on it. Thanks

[Bob B]

HMMMM, could be scaring the xxxx out of them.

Did you try to turn off the sonar and see if the bubbles went away?  That would eliminate whether it is the boat or sonar.

Sounds like it could be something getting spooked by the boat or sonar....could be crayfish scooting out of the way or something like that.

[Humminbird_Greg]

Let’s also not forget that big thing that is attached to the transducer: the boat.  Now only a fish knows for sure whether sonar affects it in any way – we can only make scientific or observative guesses at this.  But if it were me and this big thing all of a sudden looms overhead; than it would probably scare the air bubbles out of me too!

I would turn the sonar off the next time that you see this and watch to see if the bubbles quit or continue on.

[Solowolf]

From my experience (I am also dive a lot) just a sonar sound does not bother fish too much and also it depends on type of fish. Pelagic fish is much more sensitive than bottom one to any unusual things. Size of fish is also matters - the large - the less attention is paid to any irritating items. If depth is less than 30ft the boat with non-electric engine causes more problems than a sonar sound.

[Doc Stressor]

Guys, they can't detect sounds at the frequencies emitted by recreational sonar units.

There isn't anything to discuss unless somebody can come up with some evidence that they do respond in some way to your fishfinders.

The shadow of a boat and the low frequency pressure pulses given off by waves slapping against a hull have been documented to spook fish. Sonar has never been found to have any effects.

From many years of fishing patch reefs, I agree with the 30 ft rule. You generally need to cast away from the boat in water less than about 30 ft. Water clarity doesn't seem to be a factor in this. They sense the boat through means other than sight.

[sonar2000]

Actually I think this is a good discussion.
For many who were concerned about fish "hearing" sonar this topic has probably cleared up a lot of confusion.
If it has been decided that fish cant hear then the guys can stop worring about the sound and concentrate on fishing or look for other influences that may "scare" fish away.
The article that Doc references should show exactly what the fish do or dont hear or do or dont feel.
I learned a lot..

Chuck

[Doc Stressor]

There is actually quite a bit of research going on with regard to marine organisms and sonar.

The concern is that the Navy's long range acoustic listening and sensing devices may be disrupting migrations or spawning activities.

The studies are much more extensive than anything that the manufacturers of recreational sonar systems could afford to fund.

[ITGEEK]

If you've got hundreds, maybe thousands of sonar waves/beams bouncing off
a fish hard enough to reach back to the surface, I'm sure the fish knows something's
up.

Take a trophy fish in a lake that's been caught multiple times in it's lifetime.
You guys don't think that fish equates that sound/vibration/feeling with danger.
Probably has much more effect in a pond/lake/reservoir than in the open ocean or
a large Bay.

But,
I think Greg is also correct about the boat.
I think the fish will sense the boat way before it senses the sonar.

[Doc Stressor]

I've come to the conclusion over the years that most Americans must hate science, since they dismiss and ignore it all of the time.

Can you hear or feel the screech of a bat when it eco-locates it's prey? Or the microwaves that you are bathed in daily when you used your cell phone, radio, TV, or WiFi computer?

Fish sense recreational sonar as well as you can sense those frequencies.

[ITGEEK]

I have absolutely nothing against science.
I like when science can prove something beyong a shadow of a doubt.
But, there's no definitive proof that fish can't detect recreational sonar.

You said yourself Doc:

The concern is that the Navy's long range acoustic listening and sensing devices may be disrupting migrations or spawning activities.

I ask you:How can a passive system that is not sending out any sounds/beams/waves/vibrations affect the fish?
By your reasoning, fish can't detect the frequencies of recreational sonar.
So, how is it then, that they can be affected by nothing?
No sound, no vibrations. Yet these sensing devices are emiting something unnatural in their environment that may be negatively affecting them?

It's the same with sonar.
It's sounds/beams/waves/vibrations that are not natural to a fish's environment.
A fish's survival in a large part is based on knowing danger around them.
I would think that unnatural sounds would probably be perceived as danger.

Maybe some fish are not affected at all.
Maybe some fish are affected alot.
Maybe some fish get used to it and don't worry about it.
Who knows how much it actually affects the fish.

But, I guarantee fish know something unnatural is in their environment when a sonar
is pinging the hell out of the water.
I don't need science to tell me that.  It's just common sense.
If I can hear it, and sound travels 5 times faster in water, then absolutely the fish can at least sense that something unnatural is around.

I'm not saying that recreational sonar adversely affects fishing, just that the fish are most likely aware of something unnatural in their environment.  These sounds/beams/waves/vibrations can't be completely invisible to fish.

Here's a test if someone has an aquarium of fish.
Keep a sonar transducer in your tank with a sonar unit close by.
Turn on the unit and feed the fish.
After feeding, turn off the unit.
Do this over a 10 day period.
Then, turn on the unit and see if the fish are going crazy
expecting food.
I have a strong feeling they will be going crazy.

[Solowolf]

Quite a long post.
Battle ship sonars are active and very powerful.  I felt it by myself when dives not very far from the ship and fish would feel pain as well. But it is pain while fishing sonars are not painful.
Fish in not clever enough to associate some sound (even if it is unknown) with the fact it is caught. When fish sees that its neighbour is caught in most cases there is no reaction at all. You may see examples yourself on youtube with underwater camera.

[Doc Stressor]

As you should know from reading this forum, the range of a sonar unit increases with transmission output power and decreases with wavelength frequency. Naval sonar units are not only much more powerful than recreational units, but they operate at lower frequencies. Some units use frequencies within the known range of fish hearing.

Long range systems that are used to communicate with submerged submarines operate at extremely low frequencies. Acoustic listening devices, while passive, need to be pinged occasionally in order to analyze  their operational status.

[Solowolf]

I hope nobody is going to start fishing with naval sonar.
IMHO generally - there are two questions here:
1. Whether sonar itself prevents fish from "normal operation" - whether it is harmful . The answer is "generally no" since I've seen fish under the boat during the dive when sonar was working. Fish of any size was absolutely calm and happy.
2. Whether fish can associate this sound with the harm? The answer is also "most likely no" because fish even for closest neighbours can not make real conclusions and detect consequncies. The getting harm is too remote from just hearing sonar.

[mendota]

Actually, Doc, I believe that you are the one that is not getting the science right.

Let me repeat once again:  the frequency content of an impulse extends from DC on up.  LOTS of low frequency content.   (Do a bit of web research on the frequency content of pulse waveforms.)

Try taking your transducer and stick it to your temple.  Even a deaf person could feel that.   (Disclaimer - not responsible for damage to your pumpkin due to the "tiny" amount of energy.)  Consider that the coupling of the sonar pulse to the air is extremely poor, like 1%, and imagine how much more intense that pulse must be when properly coupled.  It would be foolish to think that critters with lateral lines can't detect it as well.

Finally, microwaves are an electromagnetic wave, not a vibration or pressure wave.  Completely irrelevent.

[sonar2000]

Try taking your transducer and stick it to your temple.  Even a deaf person could feel that.   (Disclaimer - not responsible for damage to your pumpkin due to the "tiny" amount of energy.)  .

So that is what happened to my brain.

Back before we had ROV's I would take a transducer and tape it to my chin. I would then (tape) a camera on my forehead and while diving I became the ROV.  Hooked to the boat by a rope....
 ..... .... ......

Chuck

[Bob B]

So that is what happened to my brain.

Back before we had ROV's I would take a transducer and tape it to my chin. I would then (tape) a camera on my forehead and while diving I became the ROV.  Hooked to the boat by a rope....
 ..... .... ......

Chuck

Hey Chuck, kind of sound like a "tow person."   

[sonar2000]

exactly......
chuck

[ITGEEK]

Right on Mendota!
You know the real deal.

[Mark Saikaley]

My personal experience has been that the sonar does not deter fish from biting nor cause them to leave the area. I have only found that using the sonar helps me find and catch more fish as I integrated the sonar and GPS into my "sixth sense" of fishing. For example, when using down riggers, in trolling, My riggers get more hits when I am piloting the boat than any other pilot who has been on the boat with me . Most are not as experienced. 

My point is whether or nor fish hear anything from the sonar, I found other factors in catching the fish are way more noticeable in catching vs not catching than if your sonar is turned on or not. I haven't been able to detect anything in that as a factor but I have noticed just about everything else is a factor. Presentation, speed, location, bait, colour, feeding activity, species, amount of time on waterand time line is in the water, (Some areas marking fish all the time have never yielded a hit while other known fishing spots with fish get more bites (same species, same lake, same time frame), which hat I am wearing etc  . Actually Id say my choice of hat has had more noticeable relationship with fish catch than if sonar is on or off. More information from the sonar helps  me figure out what is going on and thus how to compensate and catch more fish.

Ive also come to know a rainbow trout  lake so well that I fish by canoe having had portable sonar for countless hours that I don't need the sonar. Fishing it with or without the sonar or with made no impact either way on if the fish would bite. Just using the sonar proves to me there are actually still fish in this lake on says when they are not biting. Even still some days when nothing works and I'm marking fish in this lake, I start to doubt the reliability of my sonar

[slabbacks]

Interesting read.

XSilmar, my wife came unglued when she caught me testing jigs in the tank...would hate to think what a SI ducer being lowered in would do to her     or to me for that matter.




All I know is with the aid of this gear I've taken more fish on a regular basis.  If it does or dont bother them has never been noticed while fishing.  But still a good read

[ITGEEK]

Let's look at this from this scenario.
Imagine you are a huge trophy fish (any species).
You've been caught a few times in your younger days, and released (thank God).  Each time you were caught, you heard a strange clicking noise close by.

Now, you are very big, very old, and very wise.  You are trying (like anything else on this earth), to survive, and your senses are very keen. You are much, much more wary than the youngsters of your species, who are caught and re-caught several times a year.

If you hear that strange clicking noise again, will you:
A) Ignore it.  It's nothing you haven't heard before.
OR
B) Totally relax, get really happy and excited, and move towards it, expecting to feed.
OR
C) Slowly leave the area, or hunker down tight lipped (ready to haul @ss), with every sense you have, keyed in for danger.

I pick C.
Anyone else want to pick?

[slabbacks]

C,  heading to deeper water with lock jaw!