Re: NANFA-- Spawning in high water

Jay DeLong (
Sun, 27 May 2001 12:51:56 -0700


><< A lot of minnows or darters would be surprisingly
> unaffected, because the hydrology along benthic surfaces may not be as
> altered as we would think. >>
>Could you expand on this? I have always wondered how fish stay in an area
>when there is excessive water flow.

Fish associated with the stream's substrate experience little flow relative
to what's going on higher in the water column. This is due to several
- what's called a "boundary layer", where the friction of the water on the
actual substrate reduces wayer velocity there, creating calmer conditions
- the morphology some benthic fishes have evolved, such as sculpins, with
their streamlined upper bodies which the water passes over and actually
pushes the fish closer to the substrate.
- protection offered by the substrate itself, such as from boulders and
such too large to be moved by water.

Jay DeLong
Olympia, WA

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