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Understanding Fish on Sonar Posted on December 02, 2021

#1 Walleye fishing  

Side scan saved the day. the weed, sand and mud edges were easily seen. The little sand dip in the weeds is where we found walleyes. They were on the sand right next to the weeds.

No wind, clear water and sunny. Only bass shallow so we looked deeper and found some at 22 foot.

Top arrow is mud

2nd arrow is sand

3rd arrow is weedlines

Bottom arrow is weed dip

weed dip side imaging

#2 Pay attention to sonar.

 

We were using spot lock to cast for walleye and Levi said look at the sonar. I quickly reeled up and dropped my jig and caught a 4 lb largemouth bass. The 2nd photo is the bass swimming away after I released it.

4 lb Largemouth bass with sonar

4 lb Largemouth bass with sonar

#3 Fish in bait show up well.

 

Notice the 2 bright yellow arches (green arrow) in the red bait (black)

fish in bait with sonar

#4 Sonar in vegetation usually sucks.

 

I looked at lots of areas and didn't see any fish and caught fish. But here is one example where the fish showed up.

fish in weeds with sonar

Fish in vegetation, you don't have to see fish to catch them. I often don't mark fish in weeds but still catch them like this one. I spotted the fish with my Aqua-Vu and dropped my bait near the camera!

no fish in weeds

fish in weeds Aqua-Vu

Green arrow shows nice fish on down imaging but looks small on 2D. It is probably on the edge of the 2D cone and the DI cone is wider so shows the fish better.

Reason to run DI and 2D sonar. I also use Navionics on my Lowrance and LakeMaster on my Humminbird. DI (down imaging) is better in weeds most of the time.

Down imaging fish in weeds

fish in weeds 2D

#5 Difference in cones from different transducers.

 

My Garmin PS30 shows the distance to the side the fish are.

Green arrow 3 feet to the left of the transducer which is mounted on boat's mid-line.

White arrow 8 feet to left.

2D sonar only tells you how far off the bottom and that the fish in the cone somewhere.

PS 30 fish

2D sonar fish

#6

 

Red circle fish

Black arrow weeds

Green arrow small boulders on hard bottom point.

Blue arrow bait balls that create shadows on side scan.

side scan fish and weeds

This should help get started in interpreting your sonar.

 

Anglers often find fish with sonar and then they don't bite, this video explains one reason they don't. Posted on January 31, 2020

Watch Video

Find the fish, fish the fish and understand sonar with Aqua-Vu underwater camera Posted on November 14, 2019

Watch video

Understanding fish and trees on sonar Posted on October 13, 2019

Watch video

sonar and fish identification Posted on October 05, 2019

Using sonar, down imaging, Lowrance, Humminbird, and Aqua-Vu to study fish

 

watch video

Finding Panfish in weeds Posted on July 19, 2019

Finding panfish in weeds is difficult, I will share one of my methods on this short video.

YouTube video

by Bruce Samson under Aqua-Vu lowrance sonar

Fish or weeds? Posted on July 15, 2018

Just another example on why down imaging helps sonar interpretation. The weeds look similar to fish.

Weeds or fish 1

 In this one the fish look like weeds.

weeds or fish 2

Airmar TM150 setup Posted on May 28, 2018

If you use the Airmar TM 150 on a Lowrance I have found the Custom setting of single frequency 105 kHz gives me the best results. However you need to turn off the noise rejection to get those results.

The left side of this image has the default setting of Noise Rejection set at low and the right side is the Noise Rejection turned off. I don't know why this transducer doesn't perform well with the Noise Rejection on.

Lowrance TM 150 settings

Fish size on sonar Posted on October 30, 2017

Identifying fish size on sonar is very difficult since you can change the size with sensitivity adjustments or depth range. Fish look larger on a depth range of 20 foot than 100 foot. The size of a fish is determined by the color of the fish arch. For example if you have palette colors yellow, blue and red. The more yellow you see the bigger the fish. The thickness of the fish arch also determines fish size. How long the fish arch is just how long the fish is below the transducer.

In the image the black vertical lines show how long the fish is under the transducer and the green lines show the thickness of the fish arch.

fish arch

The best way to tell size is catch one the fish you see on sonar or use an Aqua-Vu camera.

The first example shows my bait dropping (green arrow), the bait is intercepted by a bass (red arrow) and the bass swims to the bottom (black arrow) and then I set the hook and catch him.

bass

This is the bass.

large bass on sonar

How about these fish. Needless to say I was excited when I found them but they didn't bite so I dropped the Aqua-Vu camera and was surprised what I found.

carp on sonarcarp on sonar 2

Watch video of fish

 On this screenshot is a 7.5 lb. northern pike, you can see when I set the hook and started bringing him to the surface.

Northern pike for sonar size educationnorthern pike

The last screenshot is smallmouth bass and I caught a few, this is a picture of one of them. One of my favorite fish to catch.

smallmouth basssmallmouth bass

This screenshot shows a 29.5 inch walleye after being released.

29 inch walleye29 inch walleye

I was lucky in my timing to collect good data to prove fish size on sonar.

Last but not least is what a 5 inch minnow attached to a sinker looks like with 1.5-2.5 lb. walleyes below it.

walleye and minnow size on sonar

 

Crappies on different sonar brands Posted on August 27, 2017

Learn how crappies display on different sonar brands.

Crappies are a much sought after fish and I get a lot of questions about what they look like on sonar. Crappies often suspend over open water, making  them  difficult to target. In this session I will show what they look like on different sonar brands.

Image #1 shows crappies on a 2D Garmin sonar using High Chirp.

Image #2 shows the same school with a Humminbird using the MEGA transducer on High Chirp.

Image #3 is the same school using a Lowrance TM150 transducer set at 105 kHz frequency.

Lowrance Crappie

Image #4 shows the same school with the Humminbird side imaging

Humminbird side imaging crappie

Next are 2 videos showing the Panoptix with 2 different transducers. The PS 30 looks down and to the side and the PS 21 looks to the side.

I use side imaging or the PS 21 to find the school when it moves since they see to the side and I use Minn Kota Spot Lock to sit on the school and vertically jig for supper.

PS 21 video

PS 30 video

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