ANTIGO, Wis. — The fact is, there’s no need to create trout habitat, adding trees, shrubs and other obstructions, to the Portage County Drainage District ditches—they’re already providing ideal habitat for brook trout.
Bob Obma, a trout fishery and watershed specialist, will tell you the only trout native to Wisconsin are brook trout (they’re actually char), and that char like cool water. In regards to cool water, Obma explains that brook trout prefer it between 62 and 63 degrees Fahrenheit, when he says they’re “happiest.”
“Anything above 68 degrees, and a brook trout doesn’t want to do anything but lie there waiting for better times to come. They sulk,” he remarks. “A brook trout will die in water over 75 degrees, but fish kills are rare in the Central Sands area of Wisconsin because of the abundant flow.”
“There are trout here in quantity,” Obma explains, referring to the Portage County Drainage District, particularly where he likes to cast a line, north of Coddington Road and south of the Village of Plover.
For trout survival, the water not only needs to be cool, but pure. It’s imperative that dissolved oxygen be more than 5 ppm (parts per million).
UPWELLING SPRINGS
Spawning requires upwelling springs through gravel, and winter habitat for larger fish includes food and deep, slow-loafing water with protection from fast currents, as in the Drainage District.
A 1955 memorandum from the Wisconsin Conservation Department found that a ditch originating in Section 12 and flowing into Ditch 2, eventually draining into the Lower Buena Vista Creek, was 75 percent sand, 10 percent silt and 15 percent gravel.
A large number of trout were found in that section of stream, which was stocked in 1954 with 425 yearling brook trout, and at the time it was “doubtful whether any value exists in stream improvement, since it was noted that pool cover in itself was good.”
Further, it was “recommended that in the future this stream not be stocked since adequate quantities of trout are found throughout its entire length.”
At the time, the stream was ranked as the fourth highest of all Portage County sections with the third highest number of young fish overall. The natural reproduction of the stream was considered excellent, and there was no carry-over of stocked trout.
A DELICATE FISH
“Brook trout are a delicate fish negatively affected by temperature and water pollution. The Portage County Drainage District is made up of clear, cool water,” Obma states.
Has it always been this way? In a 1997 fish survey of trout densities in the Fourmile/Fivemile Creek Watershed (within the Portage County Drainage District), total numbers of brook trout in tested sections ranged from 0-2,494, with most sections falling in the 2-225 range.
A score was reached when factoring in total numbers of rainbow, brown and brook trout, as well as the number of trout per mile and an IBI (biological sustainability of water) rating, and most areas rated good to excellent.
Based on the results of this survey, there are favorable habitat conditions for brook trout reproduction throughout most of the watershed.
— Wisconsin Potato & Vegetable Growers Association
For more news from Wisconsin, click here.