Trap net catch rate seemed somewhat low as was the gill net catch rate in 2007. Low amounts of northern pike might
not be a bad thing as it should allow faster growth and condition which was seen in 2007.
June, 2008 electrofishing for largemouth bass: Electrofishing does a better job of sampling bass than either gill netting
or trap netting. Again this has not been done before so no comparisons possible with other years. The catch rate or
abundance of largemouth bass was somewhat low but within the normal range compared to other lakes in the Park
Rapids area. Bass were sampled between 7.2-18.5 inches. Most were in the 13-16 inch length.
August, 2008 trap netting for all other game fish species: This is the time of year when these fish have been historic-
ally sampled so there are previous records for comparison. Trap netting doesn't work as well as gill netting for species
like walleye, yellow perch, northern pike or suckers. Gill netting works better but is not done annually because too
many fish would be killed. Gill netting was done in 2007 as a regularly scheduled population assessment so will be
done again in 2009 and with the regularly scheduled assessment in 2012.
Crappie : Abundance similar to the 2007 assessment, not real high, but within the normal range for similar
lakes but considerably higher than previous samples in 1987, '92, '97, and '02. Sizes of crappies were not impressive
in either 2007 or 2008, with none over 10 inches.
Bluegill: Bluegill netting abundance pretty high in both 2007 & 2008, but within the normal range of similar lakes.
Size has not been very good since 1997, with few if any, over 8 inches.
Pumpkinseed sunfish: Low in abundance since the initial sample in 1959.
Black bullhead: Has declined in abundance since the high count in the 2002 sampling. Black bullheads
are more tolerant of poor water quality than brown or yellow bullheads.
September,2008 electrofishing for fingerling or young of the year walleye: Some older, larger walleye were sampled
that looked like they were from the previous stocking in 2006, but no young of the year were found. This was the
second year in a row of poor electrofishing results so 410 pounds of walleye fingerlings (2,526 of them) were stocked
later in the fall of 2008.
fall of 2008.
Water Quality Monitoring Results for 2008
Date TP ChlA Secchi TSI TSI TSI TSI
ug/L ug/L ft. Phos. ChlA Secchi Avg.
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5/18/08 49 16 4.5 60 58 55 58
6/15/08 59 21 4 63 60 57 60
7/20/08 36 20 3.75 56 60 58 58
8/17/08 53 27 2.5 61 63 64 63
9/15/08 61 45 2.5 63 68 64 65
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Annual Mean 51.6 25.8 3.5 60 61 59 60
Comparing Portage Lake to other monitored Hubbard County lakes (45 were monitored in 2008.), Portage Lake had the highest Average TSI (trophic state index) of any lake-Average TSI of 60 in 2008. The next highest TSI was First Crow Wing Lake with an average TSI of 57. Big Bass Lake had the best TSI average of 32. Little Sand and Ida were close
behind with an average TSI of 34.
All three parameters TP (total phosphorus), ChlA (chlorophyll A), and the secchi depth in feet agree that Portage Lake is eutrophic. A TSI of 60-70 is considered eutrophic with dominance of blue green algae, algal scums and aquatic plan problems. Total Phosphorus (TP) is in a range of 48-96, ChlA is 20-56; the secchi depth is 1.6-3.3 ft.
A TSI of 50-60 is the lower range of eutrophication with a TP range of 24-48, ChlA of 7.3-20, and a secchi average
between 3.3-6.6 ft. Algae and aquatic plant problems are possible with "green water" most of the year. In 2008 it seemed like Portage was mostly in the lower range of the 60-70 TSI group but had individual readings in the higher part of the 50-60 category. Algal scums, "green water", unclear water, and aquatic plant problems were present from ice out till October in 2008.
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