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Sunday, October 24, 2010

Seasonal Change

Previous 5-day rainfall totaling 0.1-0.5 inches over the watershed has increased the flow, but not the turbidity, of the South Branch of the Root River. This is good news, with 98% of soybeans and 47% of corn harvested, croplands, while nearly nude, still have root structure in place that will hold soil under modest precipitation.  This bodes well for healthy redds filled with brookies and browns that will line our nets and macerate the flies of the 2013 and later seasons.

So much for speculations on the future emergence of the 2011 year-class, but, what is in store for trout already here?  Stream temperature at mid-day, October 24, was 46°F, typical of groundwater temps in the Driftless Area, and warm enough for feeding trout to begin to replenish their energy stores after the rigors of spawning. Winter gains will almost certainly be negligible, so what we have in body size now is likely to await spring to increase. Fishery biologists depend upon this seasonal interruption in growth to change the pattern of lines laid down on the surface of growing scales. Since the number of scales on an individual fish is fixed, each scale must increase slightly in area as the fish grows, to ensure that the skin will continue to cover a larger body.  Examining the scales, or, impressions of them, enables the biologist to assign an age according to the number of winter growth interruptions. Age and growth of fish, revealed through their scales, other bones, and ear stones is a time-honored pursuit among fishery biologists seeking to understand how fish populations respond to their environments.

2 comments:

  1. This is a great start to blogging! I hope you keep with it, I can tell the information you could share with everyone would be fantastic.
    Welcome to the Outdoor Blogger Network ~

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  2. It's really nice to get such scientific input from someone who really understands fishery biology and the connection between environment and organism. I really hope you keep adding this kind of info to the web network. We need more like you.

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