Sonar scaring fish?

[John]

A couple of weeks ago this subject was touched on.I presume its not the frequency that might bother the fish but rather the wattage(power?). You read about Lowrance/pinpoint etc. with 500-600 watts of power and more peak to peak as a selling point, but is this power scarring the fish.I believe Dick Knukson (sp?) said on his units they had a shallow water setting of 15 watts. Can some one enlighten me? Well.... with in reason! If a guy jigs/rigs in 20 feet of h2o or less, does he need that power, does it hurt his fishing? thanks

[Nofish]

Howdy,

Speaking as a guy who has run Lowrance and Eagle on all his boats, I can say I do not think it does spook the fish.

You have a much better chance of spooking the fish with noises you make, sudden movements and trolling motor noise than with the locator.

Dick Knutson is correct though, they do have a shallow water setting. However my experience is this would be more to the signal overpowering the units ability to read the data. Simply put, the sonar fires off a signal, it is so strong that it bounces back and forth a few times before unit can read it, the delay in time then fools the unit into reading a much deeper depth.

This works on the same principle as sound with your ears. If someone plays a tone higher than we can hear and slowly turns the frequency down till we hear it, we will thik the tone was started long after it really was.

The long and the short of it is, buy what you want based on your needs, dont worry about spooking the fish. They knew you were there long before you got there.

And in really shallow water I hardly ever use the locator.

Have fun........R

[stewart]

I think that some fish might be turned off by sonar, just like some fish are turned off by the motor.However, I guess the benefits of being able to fish more effectively because of the sonar unit outweighs the negative most times.

[woodsdweller]

A scuba diving friend who works with the Coast Guard on Lake Michigan told me he has been diving and felt the sonar from boats traveling overhead. Said it felt like tiny pin pricks through his wet suit. He concluded that fish can definitely feel sonar also. Whether, and to what extent, it spooks them is another question he couldn't answer.

[SUPERTROLLER]

I'm not saying the fish can't sense it but if they were truly frightened by it we'd never mark a fish. They'd all run from every boat above them. What percentage of boats have sonar of some kind on them? 80 to 90 % would seem about right to me. Even the pleasure boats have them. I think fish are just as disturbed by motor noises.

[Thom]

A friend and I were just talking about this the other day, with no substantial conclusion of course, because neither of us really had a clue about any definitive truth on the subject. We did,mutually, recall one thing though. A couple of years ago, mabye 2 or so, it occured to us that the Navy had done some research into the effects of their very high power sonar systems on ships. Its seems that they had often noticed that whales would tend to beach themselves not all that long after being blasted by a few zillion killowatts of energy from the S.S.Wha****name passing overhead. Of course if they came to the conclusion that Navy ships running SONAR caused whale beachings you and I would never hear a word about it but I do recall the study having been done. Then we thought about the boats where we fish, there are a lot of charter craft in the 50-60 foot range out where we go and they will typically use bottom boxes with 1 to about 3 Kilowattts of energy (that's like 3,000 watts but not measured Peak to Peak here, we're talking RMS, so figure its 10 times what you's see from a typical recreational unit). The fish in those deep waters aren't actually a while lot deeper than they would be in any lake, at least most of the time they aren't, 50 to 200 feet down is where they lurk. Anyway that high power doesn't seem to have any effect on the larger fish (tunas, sharks, or bill fish) out there or to influence the behavior of bait fish either.

On that high power shallow depth assertion. I don't know about your machine but on mine it would record every bounce of the return echo and so what I would see is the actual bottom and then, if the internal filtering didn't catch it and erase it, there would be second and possibly even third bottoms shown on the screen but they would each be at an interval that was exactly the same as the first one - so it might show a bottom at 10 feet, and then a false bottom at 20 feet and another false bottom at 30 feet and so on. Of course the machine's control software catches stuff like that and it is a very rare sight indeed. Oh, my machine puts out 350 watts, so it really couldn't be considered the boom-box of the sea, but just like anyone else I have to go through shallow water to get to the deep stuff and as a safety matter it means a great deal to me to know the depth as we steam along. There are so very few things as embarassing as parking one's boat in the sand.

As to the diver feeling pricks, well that's a new one on me. I would just have to say that he must have been getting zapped by an extremely high power unit. The reson I say that is this, energy is energy, be it expressed as sound, or light, or simply heat, its all the same at some level. So when we think about a bottom box having some power that sounds real high it might do just a bit of good to put that into perspective for a moment. A 300 watt bottom box is putting out as much energy as three 100-watt light bulbs. When you start to think about it that way the impressive numbers seem to fade just a little bit.

Oh, before another of my long-winded posts comes to an end, let me tell you about a personal prejudice of mine. I pay a lot of attention to marine electronics but anytime I see a company that advertises its units as having some amount of power PEP (Peak Envelope Power) rather than use the much more conservative RMS (Root Mean Square) method of measurement I immediately figure that is a company who's practices are driven by their marketing department, not their engineering staff. I don't want equipment made by a company like that. So anytime I see a bottom box and the adds tell me that it has 2,000 watts of power I just figure it to be junk and I move on. For those of us who rely on the more definitive measure of power it is handy to know that PEP divided by 8 gives you an approximation of RMS power.

Thom

[Phil T.]

A diving buddy claims to have seen fish bury their noses in the bottom at the approach of a boat engine, or even a drifting boat whose depthfinder was operating a number of times. Yes, he also says he can hear the depthfinder signal underwater.
So, if we're still seeing fish with our depthfinders, what percentage of what's down there are we seeing? Half, 10%, 1% ?

[Nofish]

What percentage? Like the question about a tootsie pop, "The world may never know."

Seriously.

My whole original point was that, even if the fish did feel the sonar, most often they hear us coming long before then. I also stated that in shallow water I turn the sonar off. So I guess I am sittin on the fence on this one :P

As to thoms excellent points on wattage, I do use equipment by the peak to peak people. However, using that formula, 3000 watts divided by 8 =375. My experience is this has been powerful enough for my needs. I do not mean to slam you Thom, but I too feel that peak power claims are a little misleading.

Purchase a sonar based on a whole host of things, power being only a minor one as most all sonars these days have adequate power.

Just some more thinkin from a dullard......LOL!

Have fun.........R

[Mckoz]

I have to agree with Nofish on this regarding spooking the fish - really don't know but I won't take any chances. Here are a couple of interesting quotes from a man in the know!

"Research suggests that walleyes HEAR underwater sound waves in the range of 100 to 2000 Hertz."

"The lateral line detects low-frequency sounds waves in the range of about 1 to 200 Hertz."

"Some vibrations can only be be felt (lower frequencies within the 1 to 200 Hz range), while other vibrations can only be heard (higher pitches within the 20 to 600 Hz and 3,000 to 13,000 Hz ranges). There apparently is an area of overlap in which a fish can HEAR AND FEEL vibrations (about 20 to 200 Hz)"

I don't pretend to understand all this but most transducers are in the Khz range???

Mike

[Jim Ordway]

McKoz, you outa keep this post going and convince folks that they should turn off their sonor when they find fish :). I need all the advantage I can get! Seriously, I am surprised that sonar companies have not researched this. It seems I have read in the past that sonar does not have much of a relative impact on fish. Think about all the fish you have jigged into the boat, while marking them on your sonar. I would speculate that it has little influence. That being said, sometimes, when I am perchin, I will turn it off, just in case.
Hope all is well in N Lake,

[Mckoz]

Hey Jim - yeah I need every excuse I can to return home without any fish. I was at the boat show this past week and now I think the problem is my boat - Saw a Pro V SE and I think Im in love. I'll have to look you up once you get your new boat all rigged up, I'd like to see it.

Fishin and work are both a little slow around here looks like things will pick up by March.

Mike

[vetspet(ind)]

if we are scaring fish then why do our ice units not "seem" to scare them...my unit is 1,000 watts...i can watch the fish very closely when it enters the area of cone and it does not act as if it can detect anything as i lower my bait it will ascend and take it most of the time....on our boat we do not have the luxury of watching the fish so closely....i'm not sure but it just seems like my ice unit doesn't affect fish...steve

[Texeye]

I've really enjoyed this post as I have often wondered the same thing.I run a Garmin 240 on my trolling motor and have turned it on out of the water and it actually gives off an audible clicking sound out of the water, so I have always felt that underwater it would be that much louder. I wonder if fish have a certain comfort zone much like an animal.Carp seem to have a distance they will allow you to get before they spook,whether you are running wide open or drifting along at a slower speed.While swimming you can hear a boat halfway across a lake when you are under water ...so I know that those days that I can't catch a walleye are the days they hear me leave the ramp and go hide under rocks.Guess I could get closer with a new four-stroke,I knew there was some meaning in all of this! See ya'll later I've gone to tell my wife one more reason I need a new four-stroke.

[Phil T.]

It may be due to a difference in angler pressure. That diving friend I referred to was in a heavily-used MN lake when he noticed the fish which were attracted to his bubbles dive to the bottom when even a drifing boat approached with its sonar on.

[RICKK]

Is it at all POSSIBLE,..(big accent on possible) that at times it could make fish bite BETTER?
Years ago, as a joke,..I bought a "fish caller" from the old Hurters Co,..it was called an Indian fish call,..or something similar,...those old Indians,..you gotta hand it to them,..they are resorceful,..seemed that it was a sealed soup can,..painted in layers to have the colors of a cross between a yellow pearch and a Northern Pike,...had some type of a bell inside,..when you yanked on it,.. it would "gong",..sounded something like a cow bell,...interesting that on a still day,..you could hear it while you were standing on the ice and the thing was 20 feet deep!,..
I pretended that I was serious about it,...and only took it out if things were super slow,...the funny thing about it,..when I used it,..often with in a minute or two a flag would go up,..(maybe not mine) but within sight,..before that,.everyone around us would be just doing nothing like we were for very long periods,...after quite a while,..some of the guys I fished with,..would ask me to use it,..I'm still not sure about it, as its hard to tell with these guys,...but I "think" they were being at least hopeful it might work,...my point is,..I'm not sure if this made any real difference but wondered if a semi dormant fish might hear something and respond by being a tad more alert,..thereby noticing something on the edge of his vision or stir his brain/hunger or whatever up(?) Now,..I'm not refering to walleyes here,...there were none in these waters only bass/perch/pike/pickeral,..maybe spookier fish are different. It might be silly,..but I would have to stifel a laugh every time I used it,..and how often a flag would go up.

[Ray]

John ,I had an interesting experence on Little Bay Denoc ice fishing, last week. What began as an exersise to save battery power on my portable unit,the fist day out,I left my unit off about 50% of the time. I noticed that during the day all of my bites were coming while my sonar was off, although during the evening bite between 5:30 and 6:00 I did catch a16 inch eater and a 27 inch female while my sonar was on.I continued the experement the following day, with the same results. three eaters, and a number of smaller fish between 11AM and 3PM all bit while my sonar was off. Again in th evening I got a 25 inch eye while my unit was on.I have come to theconclusion that fish can probably feel the sonar signal passing through them, and this is an annoyance during periods of rest and inactivity, and they are avoiding my sonar cone during these times.And that they tend to ignore the signal during times of high activity,agressive feeding the evening bite etc.Probably much like the dripping faucet that you don't notice until the lights are out and you are tryig to sleep.My observations and conclusions! Has any one else had similar experences?