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"The juvenile census is a 20% sub-sample of pool rearing habitats only (no riffles or rapids were sampled) using a Rapid Assay technique designed to cover large distances and succeed in describing the distribution patterns and the relative abundance of multiple species of salmonids. Beaver dam abundance and road crossing information was also collected. The juvenile salmonid abundance data presented tabularly in this document has been expanded from the 20% sample to represent an estimate of abundance for all pool habitats within a stream segment. Although estimates have been produced for all existing pool habitats this still does not represent a complete population estimate for each stream because steelhead and cutthroat both utilize fast water habitats for summer rearing. Coho expansions from the pool inventory can be used as a surrogate for a population estimate because coho summer rear almost exclusively in pool habitats. Because juvenile distribution within side channel habitats is not evenly distributed, most side channels were sampled at a 100% rate (every pool). Sampling rates for side channels are indicated within the comment field of the Access database that accompanies this report.
The abundance estimates for steelhead and cutthroat in this document should only be utilized for inter-annual trend analysis and do not represent an estimate of total abundance.
The juvenile abundances documented in the Tualatin basin during the summer of 2013 were the result of an adult escapement of 12,941 wild coho (6,571 adults/6,370 jacks) and 7,337 winter steelhead (Willamette Falls Fish Count) into the Willamette River for the 2013 brood year.
Several significant observations were made during the field work and subsequent data analysis phase of this assessment that are worth highlighting to set the stage for your review of this assessment;
1) The current range of anadromous fish distribution repeatedly fell substantially short of the range of stream miles exhibiting high-quality anadromous potential (This was likely the result of inadequate adult escapement to seed the available habitat).
2) When steelhead were present they were observed in low densities. Steelhead were not observed in the subbasins of McKay Cr or West Fork Dairy Cr.
3) Deep channel entrenchment and inadequate riparian buffers were consistently documented in lower mainstem and tributary reaches.
4) Coho are by far the most abundant salmonid species and have succeeded in capitalizing on habitat niches not well utilized by other salmonid species."
Credit: Bio-Surveys, LLC, "Tualatin River Rapid Bio-Assessment 2013 Final Report"
This dataset was created with the intention of geographically displaying the information that was collected from the Tualatin River Rapid Bio-Assessment. Stream segements were digitized from USGS quadrangle maps. Pool locations were placed along the stream segments using Linear Referencing.
The dataset allows the user to identify the total number of surveyed fish for a particular pool, as well as the type of fish species in a pool, and the number of fish per species.
The fields contained within this dataset, along with their descriptions, can be found below:
Entry– Pool identification number in the Access database
Date – The date the pool was surveyed
Basin – Basin that the survey took place in
Trib To – The main channel of the stream being surveyed
Stream – The stream being surveyed
Pool # (PoolNum) - Pool number
Random– Indicates a Non Randomly selected pool (should be removed from expansions)
Pool Type – PL(Lateral Scour)-PS(Straight Scour)-PT(Trench Pool) PX(Beaver Dam pool) -PD (Natural dam Pool)-PP(Plunge Pool)
Length (PoolLength) – Length of sample pool (hydraulic control to base of riffle), measured
Width (PoolWidth) – Average of 3 evenly spaced pool widths (estimated but calibrated for each new stream)
Visibility – 1(excellent, high confidence), 2(fair), 3(poor, low confidence)
Complexity– 1(0% cover), 2(1-25% cover), 3(26-50% cover), 4(51-75% cover), 5(76-100 cover) when viewed as a percentage of the pool surface area
Distance (PoolDistance) – Distance from the beginning of a sample pool to the beginning of the next sample pool (estimated by pacing)
Cumulative Distance (CumuDistance) – Cumulative distance from the beginning of the inventoried stream
Coho (ZeroAgeCoho) – Zero age coho parr
0+ (ZeroAge) - Zero age cutthroat and steelhead combined 90mm
Cut (Cutthroat) – 1+ and older cutthroat trout >90mm
Chin (Chinook) – Zero age Chinook parr
Sthd (Steelhead) - 1+ and older steelhead parr >90mm
Culvert– A culvert was encountered somewhere within the last measured distance
Knot (Knotweed) – Knotweed was encountered somewhere within the last measured distance
Beaver Dam (BeavDam) – A beaver dam was encountered within the last measured distance
# Beaver dams (NumBeavDams) – The number of beaver dams within the last measured distance
Comments – Any pertinent supplemental data