What was my sonar telling me?

I posted this on the South Carolina board but later thought I might want it here too for some answers so here goes. I went to the lake tonite to sink a couple more condos. Afterwards I pulled up to a sign marking a point and supposely shallow water. The depth came up sharply from the 45 ft. creek channel to 13-14 ft. next to the sign. The graph (Eagle Seafinder 480) was set to show pictures of fish instead of arches. The screen about half blacked out with fish symbols on top of that hump. It wasnt structure cause I see structure coming from the bottom upwards and there werent any trees, etc. on this hump. The fish symbols went from about 4 ft (which could be some surface clutter) and went down to about 10 ft. This wasnt in just one spot either but all over the hump. I'd say I traveled in a circle about 20 yards wide. I backed off the spot and set the sensitivity down to 55% and still saw the same thing. When I was leaving the spot and moved over the deeper water no more fish showed. Shortly I went under a brodge where the water was 50' and no fish showing. Moved to the rifraft at one end of the bridge and started seeing more fish symbols. As I started back over the deepest water no more fish symbols. Do you guys reckon those were fish I saw? What else could it have been? I know the book recommends not using the fish ID and learn to using the arches but since I'm new to using a fish finder I'm not sure about what is a fish and what isnt yet using the arches. Any opinions? Thanks.

Sounds like schools of shad. Next time you see it turn your Fish ID off for a minute and see what it shows. It will probably show big clouds of shad.

I agree Jerry...izzy

Turning the fish ID off should be the first thing you do when you first INSTALL the unit.

Sounds like shad to me, too.

I use Fish ID when I am hovering over crappie condos to help identify fish and see their depths. When you're not moving fast enough (from 1 to 3-mph depending on who you ask) fish will that remain in the "cone" or viewing area of the graph will show as solid lines without the Fish ID on, which can make them real hard to distinguish from cover. On a good quality graph the Fish ID is a useful tool for finding the area of a condo that is holding a lot of fish and selecting fishing depths to try.

The trick is to get the sensitivity of the Fish ID set properly. When we put down new brush or bamboo mine don't show any fish when I go back right over the new condo so I feel confident that when it does show fish symbols most of them are fish. When I see a lot of fish symbols in one area of the condo, set my baits to fish those depths and move them to that area and start catching fish I get even more confident that the fish symbols are mostly fish.

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Originally Posted by sac-a-lait

Turning the fish ID off should be the first thing you do when you first INSTALL the unit.

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The factory pre-set doesnt show the Fish ID, but I must not have the transducer set exactly right since I dont see good arches. Not using the fish ID I have seen what must be shad balled up together out in deeper water, closer to the top while motoring pretty fast across the lake. The couple of times I've seen this it just looked like an ob-long ball that was shaded grey somewhere around 10-15 ft deep over deep water. These fish symbols I saw tonight werent balled up together but was scattered all over the screen. Next time I see this I'll turn off the fish ID and see what it looks like. Thanks for the replies guys. I'll learn this sonar yet!

You can also get pretty strange displays when straddling two depths. The finder assumes the deeper reflection is the bottom, so the others must be fish, when it is just a different bottom depth. The transducer reads from a broad area at once.

Also realize many things will show up as fish with the fish ID, even bubbles of air caught on sticks or grass, but I agree with others here it was shad.

Learn to use the arches it's really not hard to do.