Qualitative Habitat Assessment (QHA) User's Guide Version 1.2
July 1, 2003
read full guide > (70k PDF)
Overview
The Qualitative Habitat Assessment technique (QHA) provides a
structured, "qualitative" approach to analyzing the relationship
between a given fish species and its habitat. It does this through a
systematic assessment of the condition of several aquatic habitat
attributes (sediment, water temperature, etc.) that are thought to be key
to biological production and sustainability. Attributes are assessed for
each of several stream reaches or small watersheds within a larger
hydrologic system. Habitat attribute findings are then considered in terms
of their influence on a given species and life stage.
QHA relies on the expert knowledge of natural resource professionals
with experience in a given local area to describe physical conditions in
the target stream and to create an hypothesis about how the habitat would
be used by a given fish species. The hypothesis is the "lens"
through which physical conditions in the stream are viewed. The hypothesis
consists of weights that are assigned to life stages and habitat
attributes, as well as a description of how reaches are used by different
life stages. These result in a composite weight that is applied to a
physical habitat score in each reach. This score is the difference between
a rating of physical habitat in a reach under the current condition and a
theoretical "reference" condition.
The ultimate result is an indication of the relative restoration and
protection value for each reach and habitat attribute. QHA also provides a
means to compare restoration and protection ratings to other biological
and demographic information of the user's choosing. QHA includes features
for documenting the decision process and describing the level of
confidence that users have in the various ratings.
QHA should not be viewed as a sophisticated analytical model. QHA
simply supplies a framework for reporting information and analyzing the
relationships between a species and its environment. It is up to
knowledgeable scientists, managers, and planners to interpret results and
make actual decisions regarding these relationships and the actions that
might be taken to protect or strengthen these relationships.
read full guide > (70k PDF)
 |
Documents in Acrobat PDF format
require the Acrobat reader plugin |
|
home