Any biologists out there???

[Trick]

I heard a strange statement today.

"During the fall when the leaves and carcasses fill the rivers, the decay increases the acidity of the water causing all adronomous (sp) fish in the system to darken quickly".

This statement was made by guy after catching a boot steelhead buck. My guess is that it was a late summer-run, but he thought it was a winter subjected to this harsh enviroment in the system?

Any truth to this?

[GutshotApe]

I'm not a biologist but I talked to one once :grin: .

The big influx of leaves each fall turns the water dark from the tannin that leaches out - but I think its a stretch to say that's what causes the fish to darken, or that it speeds up their darkening. Salmon run up rivers in Alaska with no trees other than willows - and those fish darken just like the ones in Oregon rivers. I think. :whazzup:

I've caught dark chinook in saltwater.

[Master Baiter]

Trick,

You may need to pull your waders a little higher for that one, the chocolate tide is comin in deep!

Arm chair biologists...

MB

[Lured In]

I am not a biologist but I did stay at a Holiday Inn Express last night. :tongue: :grin:

I have not heard of such an explanation for the darkening of the fish. While it may be true that the acidity rises, I doubt that would be the major cause of the darkening.

In the case of salmon, we all know they are essentially rotting away, even while still alive. So with salmon it may be simply attributable to that.

If I had to guess (which I am) I would say that this is a defense mechanism that enables the fish to better hide is clear/shallow rivers during spawning runs. In the case of steelhead, this cannot be permanent as they often will return to the ocean and return mint bright on their next spawning run.

What actually causes this, I have heard everything from sunburns to a reaction to fresh water in general. Surely someone must know....

[ 11-22-2002, 08:32 AM: Message edited by: Lured In ]

[Point-of-Sale Clerk]

I am not a biologist, but I played one on TV… :grin:

http://www.wa.gov/wdfw/fish/chum/chum-9.htm

[Trick]

According to the web site maybe there is some truth to it???

but they also have the ability to change colors and patterns depending on their environments

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This would be an enviroment change, but the article never touches on this type of reaction to acidity???

Maybe....maybe not???

Thanks for the link ***. Very informative!

...and thanks for playing one on TV.

[Mad Mikey]

Part of it is a chemical reaction from going salt to fresh water, something I learned in HS biology about osmosis and permeable membranes etc.
Another part of it is the spawning process. Ever notice how bucks usually get the color while the hens don't(if not as much?)
The pigment in the meat(iodine, carotene I believe) does some travelling. In hens, much of it goes to the eggs. In bucks, well we know the sperm sacs aren't red, so much of the coloring goes to the skin. That can be tough on newbies with a Winter hen that may have already spawned but still looks bright, I think we all make that mistake once or twice early on.
I've never heard the thing about the leaves, no doubt it raises the acidity of the river but I would hedge a bet the fishs' biological clock is the biggest factor.

[GutshotApe]

Eyes up! And down!

Read all the way thru the article in ***'s link and there is an interesting paragraph on fish eyes. It says if a fish is laid flat the eye on top will be looking "down" while the other eye (underneath) will be looking up.

Field test anyone? :whazzup: