take a look at my sonar image...

[The Quadfather]

I feel like a total rookie asking for an interpretation of my sonar image... but what is cornfusing is that when I see bait balls of stickleback in Lk. WA. it is clearly a "Cloud" of bait, with larger fish surrounding it.
Today on Sammamish I went through an area where I kept getting this pic. large fish, at the end of these little strings...
My finder was set to "Fish imaging" and not to raw sonar. I am aware of setting it to the raw sonar setting and seeing just the boomerang shaped arches,, but this was a little odd.

[Marc Martyn]

I have a 585C and get the same images in a much shallower lake. I believe that what you are seeing in the arches associated with the fish images are the fish itself, not bait fish surrounding a particular fish. I'm not sure, but it is possible the arches are more apt to appear when you are going in certain directions over the fish along with the sensitivity level of the finder. It may also have something to do with the finder scroll speed and the speed of the boat.
The images behind the fish symbol do appear to be elongated arches.

Contact Humminbird below and attach the above photo to your email. They should be able to explain it thoroughly. I'm curious also as to why the long arches.

custserv@johnsonoutdoors.com

[zen leecher aka Bill W]

Fish imaging will confuse bait fish and show them as small or large fish symbols based on the size of the school. You should use the arches as it will show different sized arches for different sized fish. Also the arches vary based on the size and construction of the air bladder. Schools of bait will show up as a cloud.

[Anonymous]

Quad, are you are talking about the lines showing up near the bottom? All I see on the image is some variations in water density/possible currents below 60'. These will show up as long streaks or big, shallow arches and are definetly not fish. In Sammamish you run across much more of this as you get closer to the mouth of the creek. Bait balls will typically look like a cloud or very fat arches. Take a look at the image below taken yesterday on Lake Washington. It shows a few bait balls and a serious change in water density around 100'. Not every arch and suspended tick you see is a fish, today's sonar units are very sensitive and will even pick up the path of a grebe through the water column long after it has surfaced.

[The Quadfather]

G-man, thanks for that pic. I was not aware of that this could be a change in water density as you said. The lines on my image were no way as numerous and thick as yours, but maybe it is just that... water density or some currents or something. This was though not near the creek at all. It was though in an area that had a rise/bump in the depth. Kind of near a mini mole hill I went over.

[Rollin with Rolland]

don't have the 595c, but interpretation in general; You know quad that the fish imaging setting is not the most ideal. It's best to go to "raw imaging" or flasher and interpret yourself. Like the pros have already responded, SO many factors. could be big fish, could be small fish, could be air bubbles, could be so many things. Generally schools of bait fish are easy to identify by the large "cloud" effect on all electronics (like you said). Each unit is different though......

[Marc Martyn]

Here is a picture of my 585C taken in the middle of August. In between the two greenish/blue zones, you can see little flex of the same color. I notice that in the late fall and early spring, there will be the elongated bands of the same color. During the summer, like when this picture was taken, the lake was fully stratified. In the fall the water starts to mix showing cooler water scattered all throughout the water column with long blueish streaks. That is how I know the lake is about to turn over.

This last summer I was fishing up at Browns Lake. It is a fairly shallow lake only about 25' deep. I was kicking along and would notice blue specs on the scree in two areas of the bay. They were present from the bottom to the surface on the screen. I would proceed on my way a bit further and they would disappear. Going back over it several times, they would once again appear in the same area. I took my thermometer and dropped it down to the bottom when I saw the blue specs. I then moved away from that area where I wasn't seeing the images and took another bottom temperature. There was a about an 8º variation in the two temperatures. What I was crossing over were underground SPRINGS!