A bit more info from
Handbook of Freshwater Fishery Biology Vol Two ,
Carlander pg 112 "Feeding occurred in winter in Buckeye L. , OH, ... with fat accumulating in the tissue. ... In aquaria no feeding occurred below 3.3 C ,and feeding in ponds has been found at 3.9 C. In ponds there was no growth and little feeding at temperatures below 10 C. In a Michigan lake , bluegills fed little in winter , and caldocera where the major food in mid-winter. "
10 C = 50 F
It seems to me that this is your dep. ewest?????
Her you have a link to a lecture on energetic on brown/brook trout study on local tribes from Greenland and in Norway.
On page 12 you can see that the studies are based on brook living in a temp. environemente that has rised from a averge of
C 4,9 to C 9,1 at the peek/hotest of summer(august)
http://dok.ebl-kompetanse.no/Foredrag/2008/Fiskesymposiet/Fjeld.pdfI could not fine a english version hovever I did fine translation on the particulare studie from Greenland
http://www.biomedcentral.com/content/pdf/1472-6785-6-10.pdf 3.3 C = 37.94 F
3.9 C = 39.02 F