Topic: how to identify large catfish?

[1fireball]

I have a 1198 and I fish for large catfish. I have some questions about identifying these on 2d sonar and side scan. I am new but I have hundreds of hours with my new unit. When looking for large cats I look for a hard red return on my unit witch I think is the skull of a large cat. A catfish to me looks like a red headed guppy. If there is yellow in front and behind the red ball. I assume its a carp or large striper. I think the sonar is reflecting the thick body of the other species. Now im no expert but alot of times im running over large arches witch show no red even with the sensitivity turned up to the point of clouding the screen.90% of the time I am on max mode. I have no issues identifying bait from fish. My question is am I in the right frame of mind looking for big cats? Can some of the large arches be big cats I dont run directly over and do not show the hard return? any help appreciated. I have some pics of what I identify as big cats I will post later.  I have been reading on here about the bladder showing up on large fish in down and side image. I have done no recordings and wonder if I am missing something here in my search. I know there are experts here on this subject and I would love to hear from you. Alot of times I do catch big cats I have identified my way. so I cant be all wrong but I wonder if I am missing seeing alot of Big Cats. thanks Mike

[Humminbird_Greg]

Mike,
Most likely you are missing some big cats.  If a fish passes through the outer edge of a sonar beam it will not reflect as much of the sonar back to the transducer, so a big cat at the outer edge of the 2D sonar may not look like a red-headed guppy on the screen of your 1198 unit.

If the red part is the head then it would depend on which direction the fish is pointing in relation to the transducer.  Personally I don’t think that the head is reflecting that much sonar but I could be wrong.  I’ve always heard that the air bladder accounts for 50% of the sonar return and the flesh, bone and scales for the other 50%.  Skinned fish don’t reflect much sonar from their skin.  This is all theory here so I could be wrong.

What you have been doing has proven itself; so I don’t know that I would jump up and make any big changes.

[1fireball]

I'm still a newbie but trying to learn all I can about my sonar. I'm talking about catfish 20-100 lbs.the catfish head is almost all bone and on big cats you can have a head over 8" wide.  The next thing is gizzard shad. You can tell a lot of times by the many small red returns its gizzard shad not threadfins just by the appearance on sonar. I am new to this bladder thing so I want to know if I'm missing the boat somwhere. Stripers seem to be easy to tell if there on sonar from big cats. I was not aware of the bladder returns so I definitely need to learn more. I CPR all fish...but next time I got a big cat on I'm going to try to record it and bring him under my sonar beam.

[Bob B]

You may have to wear it out pretty good.....I'd like to be watching when you try to do that.

[Dieago]

Have you ever watched this? I found it interesting on catfish from this catfish guide

Lake Tawakoni Fishing Guide Michael Littlejohn, Finding Blue Cats on Sonar 903-441-3937

This one they find three and catch one

Finding Blue Catfish on Side Imaging **ACTUAL FOOTAGE** Michael & Teri

[RGecy]

Dieago,

Great Videos! I guess we were posting at the same time!

Mike,

I would say that you would be able to see the catfish better with the side imaging as shown in the videos.  The shadow is going to be the key, not necessarily the hard return.  2D will certainly show you its a fish, but as Greg stated, unless it passes directly under, it may not register a large fish.

Check out this image with fish on the right.  Notice the shadow and how close it is to the hard return.  This indicates they are fairly close to the bottom.

Details Side Imaging Fish

Side Imaging Fish

Details Side Imaging Fish2

Side Imaging Fish2

Hope that helps,

Robert

[1fireball]

Thank you yes Ive watched Michael Littlejohn on lake Tawokoni many times. He is a expert and where I learned to look for Big Cats.  I play with my side image settings constantly and have never seen the pics like she saw on her side image. If I recall she was in 20 some fow also when she spotted the Cats. Ive been working on my transducer for 4 months problem is my big tri-toon gives interference to my side scan on the left side. I have been searching for help with my interference on another page. I wanted to know what other people on this site thought about what Littlejohn has taught me. I know there are experts on this site. I am a information gathering junky. I dont know enough but I truly enjoy learning. So many things with sonar I just dont fully understand yet.

[Dieago]

Robert In the top picture I noticed the range was only 20 meters left and right would that help in hunting these?

[Dieago]

Fireball could you make like a smaller aluminum pipe in a larger one with like a set screw lever and weld flat mounting surface for transducer mount and adjust it deeper for scouting in SI at trolling speed in deeper water? or better yet have a aluminum step down plate welded on back of pontoon for a transducer mount maybe ?  just my wheels turning

[RGecy]

Robert In the top picture I noticed the range was only 20 meters left and right would that help in hunting these?

Absolutely!  Keeping the range to around 3 times the water depth will certainly help in identifying fish.

[1fireball]

Diego yes I have extended it back and down 6 inches and it helped a little. Problem is the mount caused alot od turbulence around the ducer and I had to go 3.5 mph or slower. also it put alot of drag shooting a 6 ft rooster tail at 47 mph.   Something I could adjust from the top pf the deck might be my only answere. got my wheels turning.

[Humminbird_Greg]

I saw a mount for a pontoon boat on this or another web site.  It allowed the transducer to be moved upwards for high-speed operation and lowered for slow-speed Si operation.  Many ways that this could be done.

In the video I caught the comment made about sonar returns from the heads of the beasts.  Not sure that I believe it fully but then I don’t have the years on the water fishing experience for large cats either.  Theory is fine but cold card experience is hard to beat.  At some water depths I could see where the heads of these large cats could reflect more sonar than the swim bladder as the swim bladder may not be filled as much as at other times.  Still the shadows will help in identifying them.  Attached should be a screen snapshot I took way back in 2006 of five large fish (cats?) with the original 987c Si unit (262kHz Si).  I’ve had several say that these are not fish and that they are connected to the bottom but the shadows don’t lie.  If these were structure the shadows would be connected to the sonar returns and these are not.  Not sure why they were playing follow-the-leader, perhaps they are NASCAR fans and were practicing their draft!

Wish she would have had a 360 Imaging accessory on the boat so we know which of those fish that she marked was caught!

[Dieago]

Im not to crazy about the show but on you tube there is a show called hook n look where fisherman on boat look at sonar and divers do underwater video of the sonar returns they see. Kind of interesting. just stuff I watch during bad weather days.

Greg the thing that baffles me the most with the company you work for and sonar technology is. Where will they go next! Whats the next level? Be fun to watch and see. I guess which way the head or tail is facing only matters is if the tail is propelling the head toward the hook and bait lol

[Bob B]

If the fish are all facing one direction, it might tell you which direction to present your bait to them.

[Humminbird_Greg]

That is of course assuming that they can only be pointed left or right…

[RGecy]

How about this for future advancement!

http://www.youtube.com/watch?v=IQbijC_z3QE

[Dieago]

R that is freekin incredible!! blew me away!

[Bob B]

Pretty amazing......How many 100 thousand will one of those set you back?   

[RGecy]

Pretty amazing......How many 100 thousand will one of those set you back?   

Just 1   

Price tag is around $90,000.

Robert

[Dieago]

Did You see that! I swear I seen do not inflate past 80 psi on that tire!
OK Im not sure yet on seeing large catfish. But as of yesterday I know what a huge group of small channel cats look like.
Dropped a live bait and caught till tired on minnows. they were both hugging bottom and suspended at 30 ft in 30ft

[Humminbird_Greg]

Pictures, we need pictures of them Dieago!

[1fireball]

to make a long story short i put the transducer on a pole dropped it 4 feet under toon and still had interference. I moved the angle and it helped. I twisted it and it helped. I got the image clear and move the transducer up to the side of toon and it blacked out the left side image partly but no interference. So with the clear screen i went hunting fish and re adjusting the settings. I moved the si to 60 feet and to one side trying to see fish and shadows. I tried 455 and 800. the less distance i put the si on the grainier my picture got. Mud bottom looks like sand big sand. I could not get andy good images of fish and shadows no matter what the settings. I worked on it for hours. I can see bridge support shadows clearly and big structure but never a clear image od fish shadows. Honestly im very dissapointed with my unit at this time. If I cant get it fixed Im jumping ship. Maybe the unit itself has a issue or the transducer. I have noticed a very small crack in the transducer on the bottom side. you can barley feel it but its there. never hit anything I know of. looks like half round manufacturing crack.

[Humminbird_Greg]

1fireball,
With the Si transducer four feet under the water you should not have had anything blocking either the left or right Si sonar (unless you were not holding it near level…).  If you still had the same interference then there may be something wrong with the transducer or the unit.  Do you know of anyone else who runs a Humminbird Si unit (any model) and would let you test your unit on their boat and their unit on your boat?

Maybe you should post a screen snapshot of what you are calling “interference”.

Can post a good picture of the small crack in the transducer as well?

[1fireball]

I did not tell it well I guess...i did get the interference out with the pole and transducer 4 ft down. I also got the interference out with the transducer running so close to the side of the toon in a few inches of water that it blacked out the picture on some of the left side side image. but the squiggly red lines where gone..so after that I went fish hunting and could not make out fish shadows no matter what I did. The water was a little muddy and lots junk in the water...could that cause you to not see shadows clearly in side image?

[Humminbird_Greg]

It would have to be very muddy before it started messing with the sonar.  Did you see anything off to either side?
Grab some screen snapshots of what you are seeing the next time you are out.