Dames & Moore, 1999 - USDA Forest Service

into three rather than two species. The reference collection of specimens identified is stored in 70 percent
ethanol and archived in the laboratory.
Fish
Both electrofishing and snorkeling were employed to estimate fish populations within Railroad creek and
those streams outside the Railroad Creek drainage where reference reaches were identified. Two of the
"non-Railroad Creek" reference locations were located in the Glacier Peak Wilderness and North
Cascades National Park, both of which are "restricted use" areas prohibiting the use of motorized vehicles
or equipment. Temporary permits were obtained to allow electrofishing at these locations during the R1.
In addition to providing information on fish populations within these streams. each method was
conducted to compare the two methods (see Appendix J) and provide indications as to the most efficient
and cost effective way to monitor fish populations inhabiting these streams.
Approximately 100 meters of stream at each sampling location was identified and isolated with block nets
for both electrofishing and snorkeling. Each stream segment sampled was as similar in habitat (e.g., pool:
riffle ratio, substrate, gradient, etc.) as practical. The length and average width (n=10) of each site was
measured and recorded and the boundaries marked. Each sampling location was photographed to
document stream conditions. Snorkeling was conducted first followed immediately by electrofishing.
Snorkeling was conducted by a two-person team that swam upstream through the sampling location.
Each snorkeler counted fish within approximately one half of the stream width. The snorkelers
communicated the number, species, and size of fish observed to a recorder standing near stream. A more
detailed description of the snorkeling survey can be found in Appendix J.
After the snorkeling survey was complete, a bank electrofishing unit consisting of a variable voltage
pulsator (VVP) supplied by a I 10-volt generator was used to capture fish within the isolated sampling
location. The VVP for the bank electrofishing unit was equipped to produce and monitor variable output
(i.e., watts, amps, and voltage) to accommodate variable conditions within the river (i.e., temperature,
conductivity, hardness, and total dissolved solids). The VVP output was monitored and controlled to
minimize adverse effects on fish. Voltage, watts, and amperage used to capture fish were recorded at
each location. Temperature and conductivity at each location was measured and recorded prior to
sampling.
At least two electrofishing passes were conducted at each location. The time required (effort) to complete
each pass was recorded. A third pass was conducted to provide a more accurate estimate of the trout
population if the number of trout (rainbow or cutthroat) collected during the first pass was less than 60
percent of the total trout collected during both the first and second pass. The "60 percent" was selected as
a criterion by which a sufficient number of fish were considered removed from the population during the
first pass to provide a noticeable reduction in the original population. This sufficient reduction, in turn,
was considered to provide a reasonable indication of the original population size. However, if the number
of trout collected during the first pass was greater than 60 percent of the total trout collected during both
the first and second pass, the results of the first and second pass were used to estimate population size.
Using data from three passes when sampling efficiency is less than 60 percent, provided additional
confidence in the population estimate.
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17693-005-019Uuly 19.1999;2:07 PM:DRAFT FINAL RI REPORT