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* Metric Name: Northern California Winter steelhead Distribution  

* Tier: 2  

* Data Vintage: 06/2012  

* Unit Of Measure: Binary; 0 = not habitat, 1 = habitat.  

* Metric Definition and Relevance: Winter Steelhead Distribution June 2012 Version This dataset depicts observation-based stream-level geographic distribution of anadromous winter-run steelhead trout, Oncorhynchus mykiss irideus (O. mykiss), in California. It was developed for the express purpose of assisting with steelhead recovery planning efforts. This dataset represents stream reaches that are known or believed to be used by steelhead based on steelhead observations. Thus, it contains only positive steelhead occurrences. The absence of distribution on a stream does not necessarily indicate that steelhead do not utilize that stream. Additionally, steelhead may not be found in all streams or reaches each year. This is due to natural variations in run size, water conditions, and other environmental factors. The information in this data set should be used as an indicator of steelhead presence/suspected presence at the time of the observation as indicated by the 'Late_Yr' (Latest Year) field attribute. 

The line features (converted to a 30m raster) in the dataset may not represent
the maximum extent of steelhead on a stream; rather it is important to note
that this distribution most likely underestimates the actual distribution of
steelhead. This distribution is based on observations found in the Aquatic
Species Observation Database (ASOD) database. The individual observations may
not have occurred at the upper extent of anadromous occupation. In addition,
no attempt was made to capture every observation of O. mykiss and so it should
not be assumed that this dataset is complete for each stream. The distribution
dataset was built solely from the ASOD observational data. No additional data
(habitat mapping, barriers data, gradient modeling, etc.) were utilized to
either add to or validate the data. It is very possible that an anadromous
observation in this dataset has been recorded above (upstream of) a barrier as
identified in the Passage Assessment Database (PAD).

Examples of appropriate uses include: - steelhead recovery planning -
Evaluation of future survey sites for steelhead - Validating steelhead
distribution models.

Examples of inappropriate uses include: - Assuming absence of a point feature
means that steelhead are not present in that stream. - Using this data to make
parcel or ground level land use management decisions. - Using this dataset to
prove or support non-existence of steelhead at any spatial scale. - Assuming
that the point feature represents the maximum possible extent of steelhead
range.

  

* Creation Method: The distributions reported in this dataset were derived from a subset of the data contained in the Aquatic Species Observation Database (ASOD), a Microsoft Access multi-species observation data capture application. ASOD is an ongoing project designed to capture as complete a set of statewide inland aquatic vertebrate species observation information as possible. Please note: A separate distribution is available for summer-run steelhead. Contact information is the same as for the above. ASOD Observation data were used to develop a network of stream segments. These lines are developed by "tracing down" from each observation to the sea using the flow properties of USGS National Hydrography Dataset (NHD) High Resolution hydrography. Lastly these lines, representing stream segments, were assigned a value of either Anad Present (Anadromous present). The end result (i.e., this layer) consists of a set of lines representing the distribution of steelhead based on observations in the Aquatic Species Observation Database.  

* Credits: California Department of Fish and Wildlife Citation: Winter Steelhead Distribution [ds0340]