|Personnel from PFBC’s Area 5 and 6 Fisheries Management offices and the Coldwater Unit conducted an electrofishing survey to evaluate the wild brown trout population in the Trophy Trout area of Monocacy Creek (Section 07) in July, 2008. The special regulations area extends for a distance of 1.9 miles, from Illicks Mill Dam upstream to the upper boundary of the Gertrude Fox Conservation Area, approximately 0.3 miles upstream of the SR 0512 Bridge. This section of stream has been managed under Trophy Trout regulations since 1988. Monitoring of the trout population occurred annually from 1988 through 2001, and was reassessed in 2008. All sampling occurred at one fixed site beginning 20 meters (66 ft) downstream from the Township Road (T-431) Bridge and terminated upstream at the low-head dam located downstream of SR 0512.
Since 1988, this section of stream has maintained an excellent Class A wild brown trout population (Figure 1). Over 15 years of monitoring, biomass estimates have fluctuated from a low of 77.9 kg/ha 2000 to a high of 205.2 kg/ha in 1988. In 2008, brown trout biomass was estimated at 149.11 kg/ha. This ranked as the seventh highest estimate recorded over the time series data collection set.
The estimated number of brown trout greater than or equal to (>) seven (7) inches in length per mile has varied from a low of 729 in 1994 to a high of 1,813 in 1991. Estimates of trout > 10 inches in length per mile have ranged from a low of 225 in 2001, to a high of 673 in 1988. Estimates of trout > 14 inches in length (i.e., trophy trout size) have been consistently low ranging from three per mile in 1992 to a high of 23/mile in 1997 (Figure 2). In 2008, the estimated number of brown trout per mile > 10 and 14 inches in length was 599 and 16, respectively.
Fluctuations in the size of the brown trout population are most likely attributable to the natural variability in abundance that occurs in response to climatic events, with natural effects exacerbated by urbanization within the Monocacy Creek watershed. These factors probably have a greater influence on the abundance and size structure of the trout population than the current angling regulations. The exceptional wild brown trout population within this section of stream continues to provide anglers with a high density of wild trout in the 7 to 13 inch size range. The consistently low number of trout > 14 inches encountered during the surveys suggests that the amount of habitat suitable for larger brown trout may be a limiting factor within this section of stream. The PFBC will continue to monitor the brown trout population managed under Trophy Trout regulations, the next survey is tentatively scheduled for the 2012 field season.
Figure 1. Time series of brown trout biomass estimates for Section 07 of Monocacy Creek from 1988 through 2001 and in 2008. Surveys to assess the population were not performed in 2002 through 2007, noted as ... after 2001 on the “x” axis.
Figure 2. The estimated number of wild brown trout > 7, 10, and 14 inches per mile for Section 07 of Monocacy Creek. Surveys to assess the population were not performed in 2002 through 2007, noted as after 2001 on the “x” axis.
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