Rainbow on graph

[Beanstir]

When flat-lining for rainbow when will I ever see them on the graph? I have discussed it with my fishing partner and I say hardly ever. I cannot believe that a rainbow will ever be under your boat to register on my graph. With the fish being in the top 30 feet of water I think that this fish would move off to the side on the approach of our boat. Even if we are in deep water I do not think a rainbow would let that happen. Any thoughts on my theory? I find it hard to fish for something I do not see on the graph. I might be too dependent on my electronics.  Thanks Beanstir

Edited March 24, 2019 by Beanstir

[Gill-T]

Many times they are high enough that they disappear in the surface clutter on your fishfinder. You would have to set the zoom and power to show the top of the graph. I see them in the summer depths on Lake Ontario right before they hit a rigger line so there is nothing magical about them. 

[Sk8man]

At best any determination of species observed on a fishfinder is a "guesstimate" for starters. It is always tempting to interpret all the marks seen as trout and salmon. In point of fact whether fishing Lake Ontario or the Finger Lakes there are various species detected by fishfinders. Secondly, the "guesstimate" regarding species is usually made by noting the positioning of the mark in the water column often with reference to the water temperature noted. Again, multi-species (e.g. suspended bass) can and do inhabit these regions. Fish finders vary greatly in the cone angle of the particular transducer which largely determines what is seen while trolling - the wider the cone angle the more volume of water covered by it and the further out from the boat the information is detected to a point. What I am getting at is that there are a lot of variables involved in making an inference about the particular species of fish detected or even what they may be doing there. Rainbows are "roamers" and may be found in various positions in the water column and for a variety of reasons. Fish or trout in general may be well outside of the cone angle much of the time while trolling, and fish marked on the screen may or may not be the ones that hit the lures while trolling. Seeing the marks on a fishfinder and "connecting the dots" should always be considered an inference regardless of species targeted. Just as an example, while trolling Seth Green rigs on Seneca I have caught a bullhead estimated to be 80 ft down over more than 300 ft of water. I thought for sure when it hit that it would be a small laker The question remains: What the heck was he doing there?

Edited March 25, 2019 by Sk8man

[Knot Worthy]

 

Not sure if this is coincidence but I have 85% convinced myself of the following.  When I run out to the BlueZone (10 - 12 miles off shore) on my big outboard and then slow down to 2 mph or so to check my graph, I almost always see a good bunch of hooks within a couple of minutes in the top 30' or so.  My theory is that curious rainbow and coho in the area are attracted by the air bubbles, wake, whitewater, shadow of the boat, etc and come over to check it out.  Unfortunately by the time I set up my small 9.9 engine to troll the hooks generally seem to be gone or are fewer and further between.  Any takers on this one?  Have I deluded myself?  

[Gill-T]

Cavitation and boat moving effects what you see. You will be shocked how many fish are under your boat when in neutral-not moving esp over deep water. 

[justtracytrolling]

If you run 2 graphs and have a second transducer on a trolling motor you mark a lot more fish up in the column on the front graph. The fish that don't move off to one side or the other as you go over them will often go down a bit in the column. This is very common with walleye up high in open water. Even when I'm running all electric on my tm walleye and I'm sure other species are boat shy when up high.

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[Beanstir]

Let's say I am in 15 feet of water flat-lining and our water is crystal clear here in Georgian Bay. I mark a fish just off of bottom. Does anyone think this fish could be a rainbow? I do not think a rainbow would stay under the boat as we pass over while kicker motor is running. Not sure what game would not be spooked by boat and motor at shallow depth. This gets back to my theory of trying to fish for fish that I do not think I will see on the fish finder. Or maybe is it possible to use side imaging to see these fish that I think are not being seen on 2 sonar. I think that fish in the top of the water column will react differently in shallow water to fish in the top of the water column over deep water. Thanks for everyone's input. Beanstir

[justtracytrolling]

My experience is mostly warm water species, but when Im trolling crystal clear shallow water I use boards and stay off the fish. I don't expect to mark target fish in much less than 20 fow in those conditions with traditional sonar. I "look" for fish with side imaging in this situation. Side imaging works great even for seeing individual fish glued to the bottom as long as there isn't structure/large rocks for them to hide in. Several times I've located good schools of walleye on sand flats in 15 or so fow and worked these fish from deep to shallow without getting over them till I figured out what they wanted. As I mentioned before having a transducer on the bow puts half of your cone out in front of the boat instead of half of your cone behind you. If you have dual frequency sonar in a split screen you can see how most fish don't let you drive straight over them in shallow or high in the column scenarios. The narrow 20° cone is a blank and the 60° cone will show fish.

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