Tuesday, April 23, 2024

Can electronics spook fish?



As a licensed professional fishing guide, Michael Acosta shows you how to find them. A Granbury resident of more than 35 years, he has been fishing all of his life, and has been a licensed guide since 1998.


Many years back, I heard that your electronics could possibly “spook” fish.  I have seen discussions on the web and in some old articles where anglers claim to have better results when they turn their graphs off.  There may be some folks who still turn off their fish finder when they locate fish.  This question came up a few years back, so I did a little research on the subject. 

This notion that sonar noise can affect fishing appears to be an “old wives tale,” but old wives tales usually have some truth or validity associated with them.  The answer to this question may surprise you. It did me. 

Based on my research, I found out that certain frequencies below 100 KHZ could affect fish.  Specifically, low frequency high-powered sonar units up to around 10 KHZ can actually potentially harm fish species due to the pressure changes in their bodies due to the powerful sound wave that can propagate easily through the water.  If you want more details on this subject, I recommend that you do a search on “sonar’s effect on fish,” which will yield all kinds of information on the subject.

The good news for the angler is that the fish finders (sonars) with frequencies above 100 KHZ used for fishing are safe and are unnoticeable by the fish.  This initially was a surprise to me, as I know I can sometimes hear the “ticking” of the transducer when the sonar is on.  So what is this “ticking” noise coming from the transducer?  According to one manufacturer, this is a noise that we can hear but the fish can’t (the fish have a different audible frequency range).  This “ticking” noise is apparently the elements in the transducer sending the signal, not the sonar signal itself.

Well, what about the sonar units that use 50 KHZ or 83 KHZ for wide angle or deep-water applications?  This may be where the “old wives tale” has some validity.  Apparently some fish may detect these lower frequencies.   Will these sound waves affect the bite?  I think that anything could potentially spook a fish on certain days.  This is probably another source of the aforementioned “old wives tale.”  On a calm day with a finicky bite, any noise in the boat can potentially spook fish. At one time the sonar may have been blamed for spooking the fish. 

When fishing for striped and/or white bass, noise — as many of you know — is used to bring in the fish.  Thrashing the surface of the water or “thumping” the side of the boat can bring active curious fish to the boat.  The difference here probably is that these noises mimic active feeding fish.  I am not sure what the sonar noise will do to the fish.  If the fish are real active, most any noise may have little to no impact.    

Most of the sonars or fish finders we use in fresh water utilize frequencies around 200 KHZ.  Some have been manufactured to as high as 450 KHZ plus.  These frequencies are not detectable by fish or by humans.  I surveyed the several manufacturer’s sites and the answer is consistent that your sonar will not affect the bite.  You should not worry about turning off your graph when you locate fish.

However, there may be more than meets the eye on some of those “old wives tales.”  Many of you may continue to turn those graphs off based on your fishing experience.  If it helps your confidence, turn it off.

I personally do not worry about leaving my sonar on.  It may have crossed my mind years back, but I usually keep the graph on at all times.  However, we are always learning and we should keep an open mind when something that sounds different challenges our previous theories.  You’ll always improve if you continue to learn.



Granbury continues to be around 2 to 3 feet low.  Water temperatures are varying from the low 40s to middle to upper 40s with this recent warm spell.  Striped bass are good to 10 pounds on the lower ends on soft plastics.  Some good sand bass reports are coming in from the river near Tin Top.  Largemouth bass are good near deeper docks and main lake points and in the river near Tin Top near those deeper holes.  Big blue catfish are being taken in deep water on those colder days and in the shallows adjacent to deeper water on cut bait.  Crappie angling continues to be good to excellent on small jigs worked near structure (bridge pilings).   

The Comanche Creek Power Plant Reservoir continues to boast on limits of channel catfish and the numbers of largemouth bass.  Channel catfish are good on prepared baits and cut bait.  Baiting a hole is recommended.  Largemouth bass are good on soft plastics fished on the upper ends near points and submerged structure.  Daily catches of 40 to 80 bass are possible.  I do not have a tilapia report.   


On other reservoirs, the action in the river above Lake Whitney for striped bass and crappie is excellent.  Striped bass limits are common on jigs fished with flukes and swimbaits.  Crappie are good on small jigs worked near structure.  Whitney striped bass and sand bass are also excellent on the main lake under the birds.               

michael.acosta@att.net | 254-396-4855