The Rapid Bioassessment (RBA) project
(initiated in 1998) provides data on distribution and abundance
of juvenile coho, steelhead and cutthroat in MidCoast basins.
The survey involves snorkeling every fifth pool along the
surveyed stream reach and recording counts of juvenile fish
observed. GIS coverages of RBA data were obtained from the
Siuslaw National
Forest office. These GIS coverages were intersected
with the
6th field coverage
to produce the layers provided in this assessment (
see
shapefiles). As requested by the MCWC Tech Team, we
summarized two parameters from the Rapid Bioassessment data:
coho per sq m, and pool complexity. Pool complexity is a
visual estimate based on percent of the pool surface area
that has cover from wood, large substrate, undercut banks,
and overhanging vegetation). Values for pool complexity
can range from 1 to 5: 1 = 0% cover, 2 = 1-25% cover, 3
= 26-50% cover, 4 = 51-75% cover, and 5 = >75% cover.
We averaged the 1998 and 1999 values of coho per sq m and
pool complexity
for each 6th field in a summary layer (<i>right</i>).
We color-coded the
6th fields for coho density and pool complexity. We summed
the number of
pools for each 6th field to indicate the extent of RBA data
for that 6th
field. Sixth fields with less than 10 pools snorkeled during
1998 and 1999
are indicated with a red outline.
To
prevent underestimation of coho rearing density, we followed recommendations
in the
Rapid Bioassessment 1998 report
when we calculated average coho per sq m and pool complexity. As recommended,
we utilized data only from pools falling within the distribution of coho
for each surveyed stream. Specifically, we excluded from the average those
pools located upstream of the last pool in which coho were observed, and,
for some mainstems, downstream of the first pool in which coho were observed.
We also weighted the average values by the number of pools snorkeled in
each year to normalize results.
Spreadsheet Data: rba_sum_10oct_2.xls
Shapefiles:
1999 Data: rba99_by6th.ZIP
(all snorkel survey data),
rba99_distrib.zip
(limit of coho distrib., 1999)
1998 Data: rba98_by6th.ZIP
(all snorkel survey data),
rba98_distrib.zip (limit of coho
distrib., 1998)
Summary By 6th Fields: rba_sum_10oct.zip
Please address questions or comments
to:
Dr. Ralph Garono
Principal Investigator
Earth Design Consultants, Inc.
rgarono@earthdesign.com
Laura Brophy
Principal Investigator
Green Point Consulting
brophyl@peak.org |
homepage 
