(Salmo trutta)
For
more information about
the trout in Seven Mile Creek, contact the Minnesota Department of Natural
Resources, Waterville Area Fisheries at 507-362-4223.
Physical Description & Behavior
The Brown Trout is native to many parts of Europe and is a relative of
the Atlantic Salmon.
Length: 16-24 inches
Weight: 2-8 pounds (however in larger lake environments
they can reach up to 30 pounds)
Color: Light Brown/Tawny Black turning to silvery on
the belly
They are very cautious fish and feed mostly at dusk and night on insects,
smaller fish and frogs.
Nicknames: Brownie, German Trout, European Brown Trout
and Breac.
Habitat
• Like all trout, the Brown Trout is fairly demanding in terms of
water quality. They can’t live in polluted, warm, or acidic streams.
However, the Brown trout is remarkably adaptable and is able to live in
waters that are no longer suitable for Brook Trout.
• Brown Trout can live in either fresh or salt water.
• They have been introduced to many lakes and streams in the United
States including the Great Lakes and Seven Mile.
• Spawning occurs in the fall in streams like Seven Mile Creek.
• They are usually found in the deeper pools in the streams where
the flow is slower.
Conservation
Efforts
• The official designation of the Seven Mile Creek is ‘marginal
trout stream’.
• The Brown Trout is an indicator species, meaning that if they
can live in a stream, it is a fairly clean stream.
• In 1986 the DNR started stocking 7,500 trout in the stream. They
live for several years and can grow up to 20 inches. They are not known
to spawn in the creek yet.
• Creating more pools and directing water flow is being considered
for the Seven Mile Creek in order to improve the habitat for the Trout.
• Efforts are being made to make the Seven Mile Creek even cleaner.
• Major sources of pollution are bank erosion (producing sediments),
tile lines (nitrates) and failing septic systems (bacteria) in the Seven
Mile Watershed. It is essential that we take care of the creek if we want
to continue to have fish such as the Brown Trout living here.
In addition
to temperature requirements, brown trout need clean water to live and
spawn in. For that reason, brown trout are considered to be an indicator
species. The success of trout populations serves as a clue into the health
of a stream. A Department of Natural Resources fish survey report published
in 1996 cited "unstable flows [and] lack of pools and suitable cover"
as the predominant challenge to Seven Mile Creek's fish capacity and sutainability
issues.
What Do Trout Need?
• A
stream that maintains year-round flow and water temperatures less than
75 degree F Gravel substrate on which to spawn.
• Sufficient
oxygen levels and circulation to supply eggs with oxygen and prevent them
from being silted over.
• Protection
and cover provided by riparian vegetation.
What
Threatens Their Habitat...
• Cutting
off recharge to the spring which maintains cool water temps in the summer
and prevents icing over in the winter.
• Excessive
erosion rates that silt over spawning grounds and suffocate developing
eggs.
• No
flow in winter months (with the exception of the spring) and oxygen depleting
algae blooms stimulated by influx in agricultural runoff.
• Vegetation
is absent from the banks throughout much of the channelized portion of
the creek within the park.
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