Big Fish on a Finder?

Discussion in 'Gateway Catfishing Club' started by SmokinBarrel, Nov 30, 2009.

  1. SmokinBarrel

    SmokinBarrel New Member

    Messages:
    921
    State:
    St. Louis, MO
    Being that I only have a midrange fish finder, I seem to have difficulty distinguishing from small and large fish in deep water. Sure, I see fish, or what appear to be large fish, but how do I know if they're not large carp, or something else? My guess is that they're catfish in most instances, but I am curious as to what others may see or have on there finders?

    So, if you currently have a picture or snapshot of a deep hole with please post up, as I'd like to compare between depth finders? AND no, you don't have to show a GPS location, or anything like that, that would subject your honey hole or favorite spot at risk of us finding out. Any spot will do, just for comparison. I have a Hummingbird 545 or 645 and will post some picks next time I am out.

    I suppose when I read someone as saying, "I see big fish" how do you know they're big catfish? Maybe I or others will be able to understand their own depth finders clearly if we see different read outs or examples.
     
  2. CatHunter24

    CatHunter24 New Member

    Messages:
    715
    State:
    Dayton, Ohio
    There has been a lot of endless debate, at least with Lowrance (im not familiar with HB) about if you can tell a scale less fish from a scaled fish. Some people claim that the new HDSs show Catfish a different color than other fish, that they are more yellow red, than red, or green etc, based on how reflective and strong the signal is. Another method I have read about is on Doc Lange's website, and I believe Doc is still a BOC member maybe? About turning the sensitivity and depth range a certain way, so that you see a picture of hte bottom at say 30 ft and another again at 60 ft. If the "echo" at 60 ft doesn't show the arch from the 30 ft picture, then it likely is a catfish because the signal is too weak from its lack of scales and its absorption of some of the waves. Im not sure if thats exactly how it works or if this makes sense, but thats a couple ways I have heard of targeting big fish that are supposed to be specifically catfish. Only have heard that working for lowrance though, so not sure it will help. Many people don't like these type of methods or hearsay, and prefer to for go looking for fish and targeting the arches specifically, instead looking for structure and disregarding everything else. Many that do that have great results to show for it as well. I have limited experience so I cannot say yet which is the better method or if a combo of the two produces the best results under certain conditions etc. Not sure if this helps, and im rambling but talk to Doc or check his website if you want to learn more on the echo method.:eek:oooh:
     

  3. JEFFRODAMIS

    JEFFRODAMIS New Member

    Messages:
    2,537
    State:
    TEXAS
    bookmarking this thread..this interests me highly
     
  4. corklabus

    corklabus New Member

    Messages:
    359
    State:
    West Virginia
    Great question; I've been wondering a couple of things also since I'm quite new to the use of sonar. I have two more questions. First....On the river, how do you distingush fish from sub surface floating debis ? Secondly, I've heard so much hype about the sensitivity settings on "most" sonar units being able to track a lure, sinker, etc;, as it goes down below the boat. I sure as heck ain't been able to track any type of anything being dropped over the side of my boat. I even dropped a concrete block as a test and couldn't track it. What's up with that ??
     
  5. CatHunter24

    CatHunter24 New Member

    Messages:
    715
    State:
    Dayton, Ohio
    It depends on the quality of the unit, but it also depends on your area of view or cone. If i am on say 83 Khz on my HDS, i don't pick up lines or sinkers that well or at all. If i am on 200KHZ and looking at a narrow cone, but in more detail I can watch my lines while drifting on the screen, and watch fish come up and snatch them. The 200 Khz setting was sensitive enough one night T BULL and i called about 75-80% of the strikes successfully before a rod slammed down. As for distinguishing fish from the clutter in the river. It depends on your sensitivity setting. Surface clutter will look like a mess and a cluster, and isnt too relavent anyway.....bottom clutter and debris on an HDS appears really dense and red if its boulders or something hard, really spread out dark red if it appears to be a tree or limbs etc. It can be difficult to pick up arches sitting atop some brushy structure....but if the sensitivity is right you can usually pick them out relating to the structure. Bait fish schools and balls are red clouds (less dense than solid structure) and usually appear off the bottom or inthe middle of the water column, they can be dense or cloudy depending on the size of the school and how tightly it is clustered.
     
  6. thunderchicken

    thunderchicken New Member

    Messages:
    769
    State:
    Yuma Az
    I have wondered that question too. I have have had 2 different sonar units, and after using them for awhile you can pick up by experience what they show. The first unit I had if the fish echo was a catfish the tail part of it looked like it was broken. I only know this by seeing what they looked like on screen and then catching some of them. Almost always the fish with the broken tails were catfish I caught. I don't know why that would be but it was true for me. It does sound weird though. I doubt carp are structure oriented fish either, and a lot of echos are located on the bottom so species behavior in conjunction with sonar can help identify what they are.

    :cool2:
     
  7. SmokinBarrel

    SmokinBarrel New Member

    Messages:
    921
    State:
    St. Louis, MO
    If possible, please take several pictures of a sonar/fishfinder reading so we can compare notes and talk to each one as an example or for referencing. I hope to be on the water in the next 2 - 3 weeks, and I'll take a few snap shots and post em up.
     
  8. CatHunter24

    CatHunter24 New Member

    Messages:
    715
    State:
    Dayton, Ohio
    It will be awhile before I get on the water, like 2-3 weeks but when i do I will try to take pictures of the sonar, and maybe fire up paint, to make a guide or a key for the pictures. Thats a good idea, and would be a good way to get an idea of different interpretations and how different units look.
     
  9. afishpatrol

    afishpatrol New Member

    Messages:
    910
    State:
    indiana
    this isn't a real good view because i was moving to slow over the top of the fish and doing that, it draws out your hooks/arches. but this is a school of shad being chased by a school of white bass. I know some of the fish are white bass because i caught many of them.
    if you look there are larger fish up in the bottom of the school and lower left corner there are other fish holding tight to the bottom! walleye, catfish, white bass??? the lake has a good population of all.
    I'm not a firm believer that one can consistantly tell what kind of fish is showing on the graph at any point in time. this is an older lowrance x15 non color, in deeper water, 20-50' you can watch your jig, 3/8oz fall to the bottom, as long as it stays within your cone coverage. if you cant see this happen on your graph then more than likely your transducer is set at the wrong angle, or you are not dropping the jig in the cone coverage area.
    [​IMG]
     
  10. JEFFRODAMIS

    JEFFRODAMIS New Member

    Messages:
    2,537
    State:
    TEXAS
  11. Fishhead1

    Fishhead1 Member

    Messages:
    177
    State:
    Illinois
    Name:
    Eric
    There are several things to consider when you are talking Sonar or hydroacoustics.

    First and foremost if you have a relatively cheap model (less than $200) you will very likely not be able to get a lot of detail out of your unit. The cone is usually very small (maybe a 6-8 foot circle @ 30 ft deep, 1/2 that for 15 ft) so your field of view is very small. You'll be able to find depth and find structure and some fish targets but again your field of view and the power of the unit is small/low so it's pretty basic information.

    Sonar works on density differences of objects it hits, that's how most units can show if you are over rock/steel, clay/sand, wood, soft mud etc. Fish returns are mostly due to the fish's air bladder (scaled vs skin fish would be much less important but high-end sonar units might be able to get additional differences). The difference in density between air and water is extreme much like water versus steel/rock.

    The problem is air bladders are different sizes dependant on the species of fish. So a 12 inch Silver carp might show up the same size as a 36+ inch sturgeon. Catfish are mostly benthic (live on the bottom) and have a low to medium sized air bladders. Further compounding the issue is water pressure, the deeper the fish is the greater the water pressure, thus shrinking the air bladder of a fish. So a 36 inch fish would have the same amount of air in it's air bladder but the air bladder's size would change with depth. This is why fish can die when you bring them up from depths greater than 50 feet, their air bladders can burst or blow out their mouths (this is also why you exhale as your rise when SCUBA diving). As if that wasn't enough where the fish is in the beam and the angle of the fish relative to the sound waves also effects how strong of a return the fish gives off.

    So what is all this saying? Basically you can't truly determine size or species using basic hydroacoustics. I'm currently working with an array of transducers and sonar at Lock and Dam 26, this system is very high tech and costs well over $50,000. Even still it can only estimate sizes of fish using a mathematical equation (Love's equation) and these estimates are still not exact and plagued by the same problems (species, orientation, depth, etc).

    The possible one exception to this is the side scan high definition sonar units. They still will reflect the air bladder but if the situation is right where a large fish is sitting over a very soft or very hard bottom, you might be able to get a visual size estimate because the flesh's density is different enough from the background to decipher the size/shape of the fish.

    Now with all this said, you can still use common sense and experience to get useful information out of your sonar units, even the very cheap ones (like mine :sad2: ), just don't take it as gospel and blindly assume you can tell size, species and presence of fish based solely on whether a few pixels are lit up on your screen. Sonar is a tool that can help any fisherman, but in the hands of a good fisherman that takes time to learn to use and interpret it properly it is probably second only to "hours on the water".

    I do think this thread is worthy of a "Sticky" because a discussion with pictures and explanations of how people interpret what they are seeing is invaluable information.
     
  12. SmokinBarrel

    SmokinBarrel New Member

    Messages:
    921
    State:
    St. Louis, MO
    Andy,

    Let's see if I get this right....

    A. Other large fish on the bottom behind/underneath the baitfish
    B. Baitfish
    C. White Bass directly behind or underneath baitfish
    d. Baitfish
     

    Attached Files:

    Last edited: Dec 1, 2009
  13. JEFFRODAMIS

    JEFFRODAMIS New Member

    Messages:
    2,537
    State:
    TEXAS
    looks like a great guess to me lol
     
  14. afishpatrol

    afishpatrol New Member

    Messages:
    910
    State:
    indiana
    that is my interpretation of what i see on the graph, had i lowered my sensetivity, the ball of bait would have showed more individual fish and not so clustered. i dont generaly do a lot of adjusting of the settings unless i am moving fast in unknown water, then i'l turn up the chart speed, ping speed and sensetivity giving you a better reading at faster speeds, imo.
    i like the way you took my pic and added the lines pointing out what i was talking about. how you do that?
     
  15. SmokinBarrel

    SmokinBarrel New Member

    Messages:
    921
    State:
    St. Louis, MO
    If you have Windows XP or Vista, do the following to access MS Paint:

    1. Click on the "Start" button at the very lower left of your screen
    2. Click on "All Programs"
    3. Click on "Accessories"
    4. Click on "Paint"

    After Paint loads do the following:
    1. Click on "File" at the top left corner
    2. Click on "Open"
    3. Find your picture, or file and open it.
    4. Begin editing with the buttons table at left, and the colors at the bottom.

    Note: I had to save your sonar picture to my desktop (computer) before I could edit it in Paint.

    Hope this helps.
     
    Last edited: Dec 1, 2009
  16. afishpatrol

    afishpatrol New Member

    Messages:
    910
    State:
    indiana
    thanks for the tip, i get a little time i'l play around with it, we just got vista a few months ago....lol...still trying to teach this old plumber new tricks.


    i pulled this off a buddies website to show a couple more views to compare with.

    Paul sent me the pic below he captured from a local watershed in Colorado. We're 1200 miles apart and have a 6 month difference in time frame between picture dates, not to mention two totally different waters and a nearly 40 degree difference in water temps, but it sure looks like the schools of crappie I graphed out here this summer. Interesting...
    Paul's (Colorado):
    [​IMG]
    Mine (Indiana):
    [​IMG]




    Permalink | Comments (0)
     
    Last edited: Dec 1, 2009
  17. SmokinBarrel

    SmokinBarrel New Member

    Messages:
    921
    State:
    St. Louis, MO
    Andy, can you identify the below alpha letters....? A, B, C......
     

    Attached Files:

  18. Welder

    Welder New Member

    Messages:
    4,834
    State:
    Missouri
    I use a dual hertz greyscale Unit on the Mo River. I had to reset everything when I first got it for the turbid water. I now can pick out fish shad, bottom mud- sand, logs ect. As far a species of fish some ya just know from location. Wish I had a pic from this afternoon to post. Shad show up as clumps and balls. Big archs 5 ft down to within 10 ft of the bottom are bigheads and spoons ect. Depending where in the river big fish on the bottom are carp, buff fish ect, find most of them in swifter water over mudd and sand around bars. Cats I find close to the bottom around current breaks or depressions. I was out goofen around today looking for sauger close to the shad schools in the gasconade. Found a few lol.
     
  19. afishpatrol

    afishpatrol New Member

    Messages:
    910
    State:
    indiana
    dennis, i realy couldnt tell you for sure, i dont even like to guess unless i'm looking at my graph and catching whats underneath it, like my first pic....
    the one titled mine, indiana, belongs to a good friend that is a very very good fisherman and very knowledgable on graphs. i'm sure he could tell ya what the species are in the pic, but again he was the one catching the fish from underneath....i'm going to dig a little deeper into his website for more info, he has written several articles about the workings of sonar units that is some top notch info. he is a scientist for dow and realy knows his electronics.