Author Topic: Multiple units will not show fish at high altitude  (Read 3802 times)

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Offline Daniel944

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Multiple units will not show fish at high altitude
« on: June 15, 2012, 10:49:38 PM »
Hi All,
I personally have a 728x, my Dad has a Matrix 3D and a friend a 700 series SI unit (sorry cant remember the exact model). All three have the same problem. We reguarly go to a small dam at 1550m above sea level to fish for trout. Not one unit will show any fish anywere for over a year. There are fish there as wehave caught heaps (3-4 fish per trip). We go to another dam at about 1300m and all 3 units show only a handfull of fish (you might see 5 per day), however we still catch fish. The main lake we fish is at 1100m and the units all seem to work well, showing many fish as you would expect.

All three dams are stocked with trout, plus we catch lots of fish there so one would assume that there should be lots of fish, but none on the screen for the higher lakes?

Any thoughts?

Cheers
Daniel


Offline Rickard

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Re: Multiple units will not show fish at high altitude
« Reply #1 on: June 17, 2012, 03:49:30 AM »
Hi Daniel,
I have no experience from fishing at high altitude, but I don't believe altitude per se explains your observation. I think it has to do with the behavior of the fish. If the fishes in the high altitude lakes for some reason swim near the surface they may simply escape the sound cone. Simple geometry shows the volume of the cone gets eight times larger at each doubling of depth. That's why you usually see much more fish in deep lakes. Perhaps your high altitude lakes are deep, but that doesn't help if the fishes chose to stay near the surface. Also, fishes near the surface will likely be scared by the boat more often than fish at depth. A sidelooking Quadbeam transducer may help when searching for fish near the surface.
Rickard

Offline sjefsrafsern

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Re: Multiple units will not show fish at high altitude
« Reply #2 on: June 18, 2012, 06:55:53 PM »
try a side imaging unit and i bet fish will pop up. :) in a lot af these waters the fish is quite shy and will move away from your boat. im going to try side imaging in a similar kind of lake, in two weeks. and can post the results of that if you would like that. :)
stig

Offline sjefsrafsern

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Re: Multiple units will not show fish at high altitude
« Reply #3 on: June 19, 2012, 10:57:01 AM »
sorry dint read the post good enough. but have you tried to adjust the settings on the si unit a lot? we adjust all the time even on the same lake, to find the best setting as you need different settings to be able to see the fish in different conditions. shallow water, deep water open water. waves rain bottom changes etc all of these things will affect the ability to see the fish and make you wanna change the settings of sense, contrast and sharpness. to get a good wiew of the fish. :) zooming in and out will also make a big difference. :)

stig


Offline Daniel944

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Re: Multiple units will not show fish at high altitude
« Reply #4 on: June 20, 2012, 03:42:32 AM »
I only have the 728x, so not sure about how the others setup there units.

I understand that the fish are timid, but I should see at least one fish between the 3 of us (perhaps 20 trips between us all)??? The thing that makes me think it is altitude related is that the dam at 1300m shows 2 or 3 fish each trip then the dam at 1100m shows many fish where you would expect to find them.

Offline sjefsrafsern

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Re: Multiple units will not show fish at high altitude
« Reply #5 on: June 20, 2012, 01:30:36 PM »
I just realised that you are from australia not sweden. :) im guessing this little dam is shallow with High water temp. And the bottom is made of gravel and rocks?? If so the trout will stay close to the bottom in deep areas and close to water inlets. And it would be difficult to separate the hard returns of the fish from the hard returns of the hard bottom. :)try to set the units to one foot above bottom. And you should be able to see more fish. :)


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