While I was crabing this weekend I saw alot of fish on my fishfinder. When I got back to the ramp I was talking to a couple of guys there and told them about the fish they said they noticed the fish too. I said they were most likly dogfish and they told me that dogfish wont show on a fishfinder because they dont have a swim blatter. I never heard this before. Anyone know if this is true???

??? Never heard that before. I wonder how come we can see the bottom ?? Just kidding...I think someone was yanking your chain....

It's radar, radio frqs that bounce back, the timing is different due to different distances which gives you a description and distance of what you are looking at. Very layman's terms.

Thats what I thought! Anything dence enough to bounce back a reading will show.
When they told me that I was thinking oh yea that 20' great white that was reported in the south sound wouldnt show because it dosent have a blatter. Didnt make sence to me.

Here's a good explanation of Fish Finders and how they operate.

http://www.lowrance.com/Tutorials/Sonar/sonar_tutorial_02.asp

I believe dogfish would still show, just as a thinner, straighter line than salmon. The bladder does make some difference because the pulse made by your depthfinder will not travel through air (inside swim bladder) giving that fish a darker thicker appearence on your depthfinder.

Yes dogfish show on the fishfinder, I've been in them in the SanJuans when they were so thick fishing was impossible, the fishfinder screen was covered and you could look over the side of the boat and see them swimming around. Clear water and the fish were near the surface.

I have also heard the air bladder thing. That being said, I'm guessing you might have been seeing HAKE !!! (Pacific Whitefish marketing ploy)
There is more of them,,, and I don't think the doggies bunch up till breeding time --spring and early summer......... <img border="0" alt="[Goldfish]" title="" src="graemlins/goldfish.gif" />

Peri,
I was in southern hood canal in front of potlatch.I dont know if there are hake there or not.But these fish were all showing at about 50' to 90' and were showing as being pretty large at least they were the largest icon on my fishfinder.I might have to go back with rod and some herring and try to see whats there.

Downrigger balls don't have an air bladder either, but you can see them on the finder. Don't believe it, dogs will show just fine.

Interesting post: I don't believe most of what I see on these 200 dollar fish finders. Some show downrigger balls, some don't. Lots of times I catch fish when nothing has shown on the finder for some time, but most of the time I catch nothing when I have been watching fish show on the finder all day long. Want to see large bait clouds, cut behind a boat that throws a lot of bubbles down like a ferry or a tug boat... <img border="0" alt="[Goldfish]" title="" src="graemlins/goldfish.gif" />

Although I'm certainly not interested in shelling out the money for one, I've heard (and seen) that a COLOR fish finder distinguishes the fish on the screen using colors (red and blue). I can't remember whether I was told that the bladder made the indication red vs. blue, but if I'm not using or buying a color fishfinder it doesn't matter.

I don't rely on my FF to point out fish. I'm more concerned with the depth.

Those things on the fish finder are just computer fish, I swear....

Exactly Spawnout
Ever wonder if the manufacturer programmed a random blip in here & there so you feel like you got your moneys worth?

I dont use my finder for anymore than to see the bottom contour and bait balls and then i fish that area. All the other markings dont really mean musch to me. A friend of mine has a colored finder and yes you can distinguish your fish alittle better but still at a 150 ft do you think a 6 inch fish will show up I dont really know. This is the same goes for Radar how many times have you came up on a fiberglass boat with a inboard and were caught off gaurd when you are running it at say 4 mlie range.

Kingfisherman, I have to ask, if your in a situation (fog, darkness) that requires radar and you have a near collision with a fiberglass boat, why are you running on the 4 mile scale?
On the occassions that I need my radar it is never set higher then a 1 mile scale and usually set at .25 or .5 mile scale. I run a 1622 Furuno with a 2.2 kw radome.

A couple suggestions, 1) adjust everything manually, if you use auto settings your not getting the maximum potential out of your radar, this goes for ff and chartplotters too. 2) Don't waste to much time on that 4 mile range, you'll miss targets inside .5 miles.

If you have your radar dialed in you should be able to see logs and birds, I can.

Ignore last sentence if your radar is less then 2.2 kw.

I dont use my fishfinder for locating fish ether I use it for depth and locating bait balls. But there have been occations that I have seen fish suspended and put my bait at that depth and started catching right away. May have just been luck.

I am thinking along the same lines as you spawn....

Kinda fishy that the fishys are always swimming the same direction huh??? LOL
You'd think every once in awhile one would go the other way...

You're wasting your time if you've got your fishfinder set on "fish icon" mode... switch that stuff off, turn off all the auto filters and start from scratch... use only the amount of filter you need to get rid of the "clutter"... you'll see a lot more in the end.

AKKings, what does a radar unit like that cost? Is it LCD or CRT?

-N.

StorminN,
Your right on that and I never run my DF in auto mode. I always adjust it manully. But I cant shut off the icons on mine. The auto mode sensitivity is way too high and it will show ghost fish every where. But even with the DF adjusted down the fish I was seeing didnt go away.