Muddiness or turbidity blocks out light and decreases lateral visibility.
The weighted spinner could be considered a foreign object in the river. It really doesn’t resemble any living creature.
A case can be made that the flash of the blade is similar, at least momentarily, to the flash of a smolt, shiner or other baitfish.
Or, perhaps when fished near the bottom, a brass-bladed model faintly resembles a crayfish.
When resident trout are feeding they will still utilize cover most of the time to keep themselves from being eaten and to hide from prey they hope to ambush.
I think that a spinner looks alive and arouses the curiosity of trout. It usually represents a larger food item to the trout, especially when they are feeding on aquatic insect nymphs. Fish know innately that they need to take in more calories than they expend and the spinner probably appears to be a “good meal”. Thus, it’s “worth it” to them to leave their cover and grab the lure.
When steelhead, salmon and other anadromous salmonids leave the ocean or large lake and enter their natal or stocked stream, their primary goal is to travel to their spawning grounds and then procreate when ready.
Migrating steelhead, cutthroat trout, Atlantic salmon, and brown trout retain the ability to feed but rarely do so actively. Our five species of Pacific salmon become unable to swallow and digest food once they enter the river.
The instinct or memory to feed is still there and they will opportunistically pick up food items on their river migration. Another instinct remains present and dates back to their early river life when they were growing to smolt size.
That trait is territorialism and you can bet these fish will still defend their “space” when they return to the river.
Migrating salmonids will also be adjusting to a much shallower environment when they move up the tributaries.
They feel more vulnerable and seek cover as they travel. We must take this wariness/shyness into consideration when we fish for them.
While there will be some appeal to their feeding instinct, when we fish with spinners or other artificial lures and flies for anadromous trout and salmon, we are primarily invading their territory with the hope that they will attack the intruder.
It would seem that something large and gaudy would always be a good choice but we must remember these fish are now in a new, relatively shallow environment and it’s definitely possible to spook them with a lure that is too big or flashy.
Similarly it’s possible to scare a resident rainbow or brown back into its hide out with a spinner that is too large or bright.
The goal with all trout and salmon is to get their attention and evoke a positive response.
To do this we must match the river and atmospheric conditions with a lure that makes them mad or curious or want to eat but does not spook them. For this discussion we are going to use the weighted spinner with
French type blades as an example because they are usually the best choice when fishing rivers. But we will also touch on matching the other lures to the conditions.
As ardent stream anglers we may fish a small, ultra-clear stream on a sunny day or a large river with water visibility measured in inches on a dark, rainy day, and everything in between.
It’s usually caused by suspended sediments from runoff or high water mobilizing the stream-bottom sand and silt. Plankton can also cause turbidity, especially in rivers with impoundments on them. Rivers can also be stained with tannic acids or other compounds that decrease light penetration but still allow trout and salmon to see well laterally because the water is clear but colored.
Checking visibility or clarity of the river is the first thing I do when I arrive.
When the stream is reasonably clear you can do this by simply seeing how deep you can see the bottom. For more turbid conditions I use my net rim and light-colored wading staff. If my net rim disappears in less than one foot of depth I generally won’t fish with lures unless it’s a small creek that I know really well. From one to two feet of visibility is still kind of marginal for spinners, but if the river is not too high and you can still read the water well you can fish your lures with confidence.
As clarity increases to three feet your options increase greatly as the steelhead and trout can see most moving lures in time to nail them.
The coveted steelhead-green occurs with four to five of visibility and is prime for fishing lures. ...