Instream habitat for trout in the Driftless Area of southeast Minnesota was
degraded by agricultural which was the major landuse of the area. Rich soil,
timber, and water attracted settlers to the region who in turn removed the
native vegetation for agriculture, fuel, and lumber (Waters 1977). Large woody
debris, used to create and maintain fish habitat naturally, was eliminated
(Hicks 1991). Increased flooding, erosion, and sedimentation was caused by
settlers who plowed the uplands and logged and pastured the slopes (Waters
1977). The sedimentation covered the stream bottom and stream bank vegetation
(Trimble and Lund 1982). Interestingly, the brown trout is not native to this
region but is more suited to the warmer and murky water than the native brook
trout (Becker 1983).
Land use of this region has improved; erosion and
sedimentation has decreased and infiltration increased (Trimble and Lund 1982).
However, the instream trout habitat has degraded. Flooding prevented natural
habitat from thriving because native stream vegetation had been replaced with
agriculture or had not been growing long enough after restoration (Thorn 1992).
It may take 25-100 years for stream corridors to produce woody debris to begin
restoration of pools, riffles, and trout cover (Armentrout 1991). Habitat
improvements have been made occasionally since 1950 in these streams, and
habitat improvement projects have been funded annually since 1970. Hay Creek,
located in this region, was improved in 1979 (Thorn 1/88).
Hay Creek runs
through Goodhue County, Minnesota at T112N and R15W. The major water source for
the stream comes from water seepage and springs located at the mouth of the
stream (Thorn 5/88). Gentle gradients occur in the upland agricultural areas,
but where it drains into the Mississippi River it has eroded through the
limestone bedrock, forming rough valleys with hardwood covered slopes. Land use
was pasture at the Hay Creek study area and before improvement, stream banks
were nonvegetated and severely eroded. Only eight meters of OBC (Overhead Bank
Cover) was present and low quality pools provided the remaining trout cover
(Thorn 1/88). An increase in the number of anglers was not logical until
habitat improvement increased the standing crop of trout (Thorn and Hawkinson
1978). Success of stocking to increase standing crops has been limited by poor
survival of stocked trout (Johnson 1983). Trout stocking ended in Hay Creek in
1982.
Habitat improvements in Hay Creek were planned and completed by
Fisheries Management (DNR) and headed by Mark Ebbers. This stream is a
representative for other agriculturally degraded streams. About 19.5 km of Hay
Creek is managed for brown trout (Salmo trutta), blacknose dace, white sucker,
and brook sticklebook (Thorn 1/88). I assume the species other than the brown
trout are managed for just because they thrive in the same habitat as the game
fish. Hunt states,"... the goal of habitat improvement is to produce larger
trout...". During 1978-79, 1.2 km of Hay Creek was improved at a cost of
$25,561/km. Included in this habitat improvement was the addition of three
instream structures (adding 60m of permanent OBC), and 635m of streambank was
riprapped with large rock. A 657m section of the middle of the stream project
was fenced annually with single strand electric wire to exclude cattle during
the summer (Thorn 1/88).
The improvements to the stream all improve habitat
for the trout, but in different ways. OBC was constructed by pounding pairs of
five-foot long wooden pilings into the stream bottom and nailing stringer planks
of green-cut hardwood across the tops of them. These stringer planks provide a
support for the green hardwood planks nailed on top of them parallel to the
stream bank with a width of three to five feet. Stones, dirt, and seed are
placed on top of the deck to construct a new streambank. Stream flow, confined
by the artificially narrowed banks, scours a pool under most of the length of
each structure (Hunt 1988). They provide shading, which minimizes thermal
stress from solar radiation, overhead cover for fish, and provide shelter
(Simonson 1988). Another attempt at habitat improvement was riprap. The idea
behind the use of riprap was to reduce erosion of stream banks and provide
hiding cover by the space between the rocks at an inexpensive price. Heavy
equipment was used to slope the eroded banks to a 30-45 degree profile.
Truckloads of rock are then dumped down the slope to create a five foot base.
The soil is then pushed back over the top of the rocks to create a more
aesthetically pleasing appearance (Hunt 1988). The final measure taken to
improve stream habitat was fencing the stream off from cattle. Cattle exclusion
was expected to allow the growth of riparian vegetation, narrowing and deepening
of the stream, and development of undercut banks (Hunt 1988).
The habitat
improvements to Hay Creek were evaluated three years and seven years after the
initial intervention. The physical characteristics measured were as follows:
pool, riffle, and total lengths; pool, riffle, and total area; pool, riffle,
and average width; pool area with water >46cm. Physical characteristics during
the summer were also compared before and after cattle exclusion on both the
fenced and unfenced area (Hunt 1/88). The most important physical change in the
stream was the increase in area deeper than 46cm. Most of the physical
characteristics within the first three years after the habitat improvements.
Physical changes in fenced and unfenced areas of the improved area were similar,
therefore, summer fencing did not improve stream morphology (Hunt 1/88). An
increase in brown trout biomass and density was noted and attributed to
increased overwinter survival or movement into improved areas and not to changes
in growth. The increase in overwinter survival was attributed to the increased
cover provided by OBC, riprap, and aquatic vegetation (Hunt 1/88).
Angling
pressure may have reduced the rate at which brown trout responded to habitat
improvements of Hay Creek (Hunt 1/88). Research done by Hunt recommends that
long-term angling rates should not exceed 40% for brown trout greater than 150
mm. Hunt also believes the benefits from habitat improvement in Hay Creek
outweigh the costs of habitat improvements. A projection over 25 years, since
the beginning of the habitat improvement to this stream, reveal that the annual
cost of the improvements is $1,282 and the state would bring in $13,390 annually
from anglers. This produces a $12,108 in revenue for the state (Hunt 1/88).
Investigations into habitat improvement techniques and long-term management
have been researched since the evaluation of Hay Creek habitat improvements.
Riprapping has little relation to trout population characteristics and is very
expensive, it should be used only for erosion and not as a primary source of
cover. Rocks function as energy-saving feeding sites rather than cover from
predators for brown trout (Hunt 5/88).
Instream habitat devices manipulate
stream characteristics, and accelerate recovery of damaged streams and provide a
short term solution for stream restoration until long term goals are met (Swales
1989). Therefore, short-term management (20-25 years) uses OBC to provide
immediate cover for trout and provide deep water for larger trout, and riprap to
reduce bank erosion. Long-term management (>25 years) should consider variables
to maintain cover and habitat complexity after in-stream work deteriorates.
Long-term land use changes may restore meandering to increase stream length and
reduce gradient, pool length, and velocity, and improve riffle quantity and
quality (Hunt 1992).
In conclusion, this project lacks a few aspects of the
restoration process. As eluded to earlier, the main objective of this project
was to improve brown trout habitat to increase the size of fish and the number
of anglers. This interest in one species creates a stream corridor habitat that
is not diverse. In affect, the DNR was mainly interested with re-vegetating the
banks with plants that would limit erosion and provide OBC and not with plants
that would improve overall habitat of the stream corridor. There was no mention
of trying to restore the natural plant communities that existed before
degradation. Diversity is important in most ecosystems; therefore design
projects should meet the broadest habitat requirements that can be encompassed
while still meeting basic objectives (Seehorn 1992).
When setting goals,
consider not only the target species, but also the associated community
organisms and overall aesthetics of the program. Even though summer fencing did
not produce changes in the stream channel of Hay Creek, anglers preferred the
fenced section for aesthetic values and lower turbidity. This was the first
mention of ecosystem or aesthetics through all of my research. More
consideration should be given to the aesthetics and multiple functions of the
site; a trout stream bank could also be used as bike or walking path while
maintaining its ecological integrity.
Will a holistic look at the stream
corridor and its appearance become important criteria or just a passing thought
for habitat improvement planners. Jumping up a scale to the watershed rather
than the stream itself is a recent development. The problem may lie in trying
to get different governmental departments to work together. For example, a
stream that lies in two different counties may not be restored in the same
manner due to the lack of communication. For this reason working at a watershed
or eco-region scale makes sense.
I question as to how severely degraded must
a stream or watershed be for the DNR or Trout Unlimited not to accept a project
proposal. If the water quality was so poor that very few species were able to
survive would the project still be proposed? Even though I question this being
a restoration project that improves the whole ecosystem I can not find fault in
the improvements this project and others like it have done to reduce problems
within the watershed.
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Hicks, B.J., J.D. Hall, P.A. Bisson, and J.R. Sedell. 1991. Responses of salmonids to habitat changes. Influences of Forest and Rangeland Management of Salmonid Fishes and Their Habitats. American Fisheries Society Special Publication 19, Bethesda, Maryland.
Hunt, R.L. 1988. A compendium of 45 trout stream habitat development evaluations in Wisconsin during 1953-1985. Wisconsin Department of Natural Resources, Technical Bulletin #162.
Johnson, M. 1983. An evaluation of stream trout stocking in Langlade, Lincoln, and Marathon counties, Wisconsin Department of Natural Resources, Bureau of Fish Management, Report #114.
Seehorn, M.E. 1992. Stream habitat improvement handbook. United States Department of Agriculture, Forest Service Southern Region, Technical Publication #16.
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Thorn, W.C. 1988. Brown trout habitat use in southeastern Minnesota and its relationship to habitat improvement. Minnesota Department of Natural Resources, Division of Fish and Wildlife, Section of Fisheries Investigational Report #395.
Thorn, W.C. 1992. Validation of a trout habitat model for planning stream habitat improvement projects. Minnesota Department of Natural Resources, Division of Fish and Wildlife, Section of Fisheries Investigational Report #394.
Thorn, W.C. and B.W. Hawkison. 1978. A three year creel census of trout streams in Goodhue, Wabasha, and Winona counties, Minnesota. Minnesota Department of Natural Resources, Division of Fish and Wildlife, Section of Fisheries Investigational Report #15.
Trimble, S.W. and S.W. Lund. 1982. Soil conservation and the reduction of erosion and sedimentation in the Coon Creek basin, Wisconsin. U.S. Geological Survey Professional Paper 1234, Washington, D.C.
Waters, T.F. 1977. The Streams and Rivers of Minnesota. University of Minnesota Press, Minneapolis.