ISFAPPC04246

• Case Number: 00CW0101
• Stream Name: Fourmile Creek
• Watershed: Fourmile Creek
• Water Division: 2
• Water District: 12
• County: Fremont
• Instream Flow App - Doc Type: Supplemental Data

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The number of brown trout per acre decreased at the Lion's Restoration site (77/acre-
92/acre) farther down the river. In 1995, a different brown trout population pattern was
found. Fewer brown trout were found in Fourmile Creek downstream of Cripple Creek
(253/acre-293/acre) compared to downstream of the Carlton Tunnel (559/acre-646/acre).

The number of brown trout per acre hi Fourmile Creek at the site downstream of
Cripple Creek'decreased from 1994 to 1995, L.ikewise, the number of brown trout per acre
present in Founnile Creek downstream of the Garlton tunnel decreased from 1994 to 1995.
Thus, in 1995, two different declines in brown trout numbers were observed, First there
was a decrease from 1994 to 1995. Second, there were fewe'r brown trout in 1995
downstream of Cripple Creek compared to downstream of the Carlton Tunnel, a difference
that did not exist in 1994.

L.ength frequency distributions are another type of analysis that can be used to
examine fisheries data. A length frequency distribution sums the number of fish of different
length groups present at each station to separate different age fish. Trout species spawn
only once a year, Eggs of a species hatch about the same time and all fish grow at about
the same rate for at least the first few years of life. Thus, a year separates the birth of
different age classes of trout. Each age class corresponds to a discrete grouping along
the length frequency distribution at least for the first two years of growth. Older fish grow
at a slower rate, and these age classes overlap on the fish distribution graph. Typically
brown trout hatch in April or Mayor in warmer streams, as early as March. On Fourmile
Creek, fish less than 70 mm in length collected in fall were considered "young-of-the-
year," meaning they hatched in the spring of that year, Young-of-the-year brown trout
were collected at only three sites: downstream of Carlton Tunnel in 1994 and upstream
and downstream of Cripple Creek in 1995. Trout from 90 mm to 150 mm in length were
a year old. Brown trout from 170 mm to 250 mm were considered two years old. All fish
longer than 250 mm were grouped as three years or older. Separation of two-year-old fish
from all older age classes was not possible in some cases due to the overlap of length
frequencies, Currently only two years of data ~re available, Future monitoring will clarify
the length distribution and growth of Fourmile Creek brown trout.

At least three age classes of brown trout were present at all Fourmile Creek sites
(Figures 8-14), The-two-year old trout age class was not clearly separated from the next
older class. Young-of-the-year brown trout were collected at only three sites, downstream
of the Carlton Tunnel in 1994 and upstream and downstream of Cripple Creek in 1995.

3.3.1.2 Minnows

L.ongnose dace and white suckers were present in Fourmile Creek (Table 12).
Numbers of longnose dace varied as the stream flowed from Cripple Creek to Canon City,
In 1994, fewer longnose dace were found in Fourmile Creek downstream of Cripple Creek
and downstream of the Carlton Tunnel than at the downstream control site (Fourmile Creek
at the Uon's Restoration site). In 1995, the number of longnose dace upstream of Cripple
Creek was higher than in the stream at the two adjacent downstream sites; Foun:nile Creek