For thise who didn’t venture out today or have a chance to walk along a freestoner, the clear skies and snow cover last night dropped the air temp low enough to produce frazil ice in Hokendauqua Ck, Northampton Co and ice flows on the Lehigh R.
Yes that's it. I couldn't put it together, but I recall that. I now just looked it up.I guess frazil ice becomes anchor ice when it clings to the stream bottom and other submerged things?
Happy New Year Mike. Very interesting information. I particularly like how you correlated the harvest insignificance. Well played sir.Frazil ice is noteworthy not because it floats, but because it is suspended in the water column when water super-cools. It’s much like a half melted slushy. As such it accumulates on rough stream bottoms, on the faces of upstream facing boulders, etc. When accumulations are great enough it can lift a stream partially out of its channel, causing it to flow overland or into high flow side channels, trap fish or strand fish on land when it recedes. It can also entrap fish in mazes of ice within stream channels. Additionally, as it melts and masses begin to float upward they can lift surface gravel from the bottom, destroying redds and dislodging macroinvertebrates. It can even occur in normally warmer limestoners when air temps are particularly cool, as in below zero or close to that, but will disappear before you have finished your morning coffee. So you wonder about high total mortality of wild trout,i.e. total mortality of 60-65% per year for age 2 and older, despite the very minor harvest effect (avg of 11 trout harvested per stream mile in Pa)?? The winter environment is probably the biggest factor.
Isn’t it interesting when something so common in nature has been staring you square in the face all of your life, but you never noticed or knew about it? I think Frazil ice is one of those natural phenomena that fit into this category for most people. It was for me until I was 22 yrs old and learned about it in Robert Butler’s graduate level fisheries behavioral ecology course at PSU.