Do salmon show on FF's?

First fish finders only work by bouncing signals off of stuff that is a different density than water. That would be stuff like rocks, metal, plastic and air.

Second, Salmon do not have airbladders. Plus all the fish I know have bodies the same density as water.

So, mostly you can't see salmon on fishfinders, but sometimes you can. Here's how it works: Salmon gulp air from the water, so sometimes they can have some air in them, but usually not much. A salmon will show up about like a herring or something, one small dot on the screen that looks like a bit of static. Now if you get your fish finder all dialed in perfect you might be able to see a salmon, but you wouldn't know what it was most of the time because one little dot in a system where you are looking for arches is like a needle in a bale of hay.

As for the guy who says he saw a demo of a salmon taking a bait at 100 feet and getting reeled to the surface, I'd bet someone is selling fishfinders and using edited film to con people. I've heard some freshwater fisherman say they can occasionally mark salmon. That might be true. They have fresh water conditions which are more optimal for a fishfinder. They also are operating at depths less than 40 feet most of the time and that helps too.

If you find yourself listening to someone that says they see salmon on the fishfinder all the time, I'd bet you they won't have one picture of all the big fish they told you they caught!

So that means you can't mark trout either?

I am like JTF on this one I used to mooch a lot on my PB and had a middle of the road Lowrance FF. I swear at times I could see salmon underneath schools of bait attacking them and the bait would condense into a ball or surge to the surface. But I have to admit the times I have caught the most salmon I couldn't see them at all.  One time that sticks out was at HMB just north of the green can I was mooching and I was on top of a school and everytime I lowered my bait I got hit probably hooked up 25-30 fish in a hour and my FF screen was totally blank. I thought it was broken but I could see bottom and as soon as I moved over a reef I was marking rockfish. Weird maybe mooch is right and they are God's fish?

Good post.  It's nice to learn more about all of this.

I too like the mystique of not using a FF, but I've come to a point where I can admit that a big reason I don't like them is because I don't have one!     So many of my trips are spur of the moment to catch an hour or two of rare flat water up here, so I have to max my use of the available time.  I throw my stuff in the truck, speed to the beach, throw it all in the water and go out as fast as I can.  I've also always looked at them like they're too bulky for my rough style.  Someday when I get my cool new boat, maybe the unsinkable Xtreme, I'll get one of you electronics gurus to rig it with a FF for me - anyone up for trading the rigging for a guided fishing trip in Humboldt?   

I may actually like the electronics, but I do feel the best fishfinder is on the end of my line!

AB-you'll love it.  It can help you find snails to....snailfinder?

You saying you'll rig me, Sean?

Snailfinder?  I doubt it!  I find most of the biggest ones in water too shallow for a FF anyway...   

Sure...it'll give us an excuse to hang out.

I have never used my Lowrance ff in the saltwater for salmon but have used it to mark salmon in the delta. I don't think the speed of a salmon would cause the ff not to mark fish cause I've marked fish going 70 mph in my bass boat. When the salmon show up I do use the ff to help locate them.

Seen a lot of trout on my finder.  But, that is freshwater and usually under 50ft deep.  Also, out salmon fishing at Linda Mar we are mainly looking for bait on our meters.  It is hard to pick up Salmon.  Don't think I have ever seen one on my fishifinder.

Ken kickfish

I've heard this "salmon don't have air bladders so they don't show up on fish finders" argument hundreds of times and it is just plain wrong. Salmon do have air bladders. Now, if it is true that the way fish finders work is that they detect the differences in density in a fish's air bladder (I don't know this to be a fact, I don't claim to know how they work), then a fish finder will surely see a salmon. If it works some other way, then I'm willing to consider the next theory.

From Great Canadian River's Salmon Undercurrents publication:

How the Air Bladder Works

Buoyed Up The gases in the air bladder, mostly oxygen and nitrogen, prevent the salmon from sinking by making it more buoyant. The salmon can stabilize itself in a hovering position by adjusting the volume and pressure of gas to a neutral position. (The neutral gas level in freshwater is slightly higher than in saltwater.)

When the salmon needs to move deeper into the water, it releases some of the gas to become less buoyant. When its ready to move upward, gas in the bladder expands to make the fish lighter. Fish that change depth frequently, such as salmon, tend to have high oxygen levels in their bladders because it fills in faster and leaves faster than other gases.

From Alaska Game and Fish's class room dissection activity:

8. Remove the swim bladder that is attached to the esophagus by stripping it out from the front with your fingers. Would anyone care to demonstrate how the swim bladder can be inflated?

    * Most fish are able to adjust the amount of air in their swim bladder so that they are able to stabilize their movement within the pressures of the water. Notice that the swim bladder is just below the spine, which is just below the center line, or the center of balance of a fish. This is why fish float upside down when they die.
    * When a fish, such as a salmon, is deep in the ocean, it adjusts the amount of air in its swim bladder so that it can hover comfortably without sinking or rising in the water. If it wants to come up to the surface, it must release some of this air, something like a burp, in order to hover at the higher depth. Some bottom fish, such as a rockfish, are unable to adjust their swim bladders by burping, and this is why when a bottom fish is caught and brought to the surface its stomach protrudes into its mouth: the swim bladder has expanded due to decreased pressure and is forcing the internal organs out through their throat.

here's a post from Stu earlier.....

http://www.norcalkayakanglers.com/bb/index.php?topic=1179.0

Joel,

You need to get a Raymarine E120.  Only issue is where to mount the dome?

My cousin's husband has it on his boat and it is amazing!!!  I thought his old color FF/GPS unit was cool, but this thing is SWEET!!!!  On our way out, he split this big color LCD screen 4 ways.
 
  1.  Typical color FF view (no big deal)
  2.  GPS Map view (pretty cool), but similar to his old unit.   
  3.  Same view as #2, but via Radar (very cool) now you can see other boats relative to you and your waypts.
  4.  Under water 3D view of the bottom.  EXTREMELY COOL!!!  Combine this with the FF view and you'll almost think the unit is worth its price.

PS, I don't believe any of us with our "cheap" units can see salmon in the ocean.  If you see a mark, something is making it, but its just not a salmon.

Stuart

I don't think the speed of a salmon would cause the ff not to mark fish cause I've marked fish going 70 mph in my bass boat.

Man, those have got to be the world's fastest fish!

I've heard this "salmon don't have air bladders so they don't show up on fish finders" argument hundreds of times and it is just plain wrong. Salmon do have air bladders. Now, if it is true that the way fish finders work is that they detect the differences in density in a fish's air bladder (I don't know this to be a fact, I don't claim to know how they work), then a fish finder will surely see a salmon. If it works some other way, then I'm willing to consider the next theory.

From Great Canadian River's Salmon Undercurrents publication:

How the Air Bladder Works

Buoyed Up The gases in the air bladder, mostly oxygen and nitrogen, prevent the salmon from sinking by making it more buoyant. The salmon can stabilize itself in a hovering position by adjusting the volume and pressure of gas to a neutral position. (The neutral gas level in freshwater is slightly higher than in saltwater.)

When the salmon needs to move deeper into the water, it releases some of the gas to become less buoyant. When its ready to move upward, gas in the bladder expands to make the fish lighter. Fish that change depth frequently, such as salmon, tend to have high oxygen levels in their bladders because it fills in faster and leaves faster than other gases.

Salmon do not "surely" show up on a fish finder. While salmon have a small air bladder it is nothing like the bladder of a bass or a rockfish. Bass and rockfish will hand out over a specific depth for a long time and have large air bladders. If you've ever caught an released a rockfish you will note that the bladder protrudes from it's mouth from excess air and the fish cannot swim back down to where it was. This is because the air in it's bladder at say 100 feet expanded to over three times the volume when it was brought to the surface.

Salmon when you reel them up from a 100 feet do swim right back down with no problem. That's because they gulp air from the water to fill their little air bladder and don't use very much air. It would be hard for them to feed if they had big air bladders because they make speeding surges straight up through bait schools to feed. They need to be able to go up and down fast, so they don't use very much air, hence they only make a dot on your fish sonar.

I have used a fish sonar for 6 years or so, and primarily fish for salmon in the ocean. I have never seen a salmon on my fishfinder! I have seen thick schools of bait fish with blank streaks going up throught them where salmon have bursted up through the bait to feed.

The primary function of my fishfinder is to find schools of bait and survey the bottom.  Bait schools mean bigger feeding fish could be around. Surveying the bottom is nice when you are drifting over structure and want to adjust you fishing depth to keep from hanging up on the bottom.

The most useful tool for salmon fishing is you GPS. Where there is one salmon there is nearly always more, so mark your catch a fish that spot for awhile. Also, I have found that returning to the same place you have GPS's, will over the years,  find more salmon.

 When you think about it, the fish finder only tells you when have passed over the bait, it doesn't find the bait. So, a lot of the fish (salmon) I caught could be located without a fishfinder! This is mostly true for salmon other fish like bass are a different story.