7727

• UCREFRP Catalog Number: 7727
• Author: Stuber, R. J., G. Gebhart and O. E. Maughan.
• Title: Habitat Suitability Index Models
• USFW Year: 1982.
• USFW - Doc Type: Green Sunfish.
• Copyright Material: NO

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Interpreting Model Outputs

The green sunfi sh HSI determi ned by use of these models wi 11 not
necessarily represent the population of green sunfish in the study area.
Habitats with an HSI of 0 may contain some green sunfish; habitats with a high
HSI may contain few. This is because the population of a study area of a
stream does not totally depend on the ability of that area to meet all life
requisite requirements of the species, as is assumed by the model. Models
which are good representations of green sunfish habitat should be positively
correlated to the long term average population levels in riverine and
lacustrine environments where green sunfish population levels are due primarily
to habitat related factors. However, this assumption has not been tested.
The proper interpretation of the HSI is one of comparison. If two riverine or
lacustrine habitats have different HSI's, the one with the higher HSI should
have the potential to support more green sunfish than the one with the lower
HSI, given that the model assumptions have not been violated.

ADDITIONAL HABITAT SUITABILITY INDEX MODELS

Model 1

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Optimal riverine habitat for green sunfish is characterized by the follow-
ing conditions, assuming that water quality is adequate: warm (> 200 C),
stable summer water temperatures; sand and small gravel substrate in at least
50% of the stream; at least 50% of surface area in pool s at average summer
flow; at 1 east 50% of the stream surface area has i nstream cover (such as
vegetation, logs, or deb~is); and current velocities are < 10 em/see at average
summer fl ow.

HSI = Number of above criteria present
5

Model 2

Optimal lacustrine habitat for green sunfish is characterized by the
following conditions, assuming that water quality is adequate: warm (> 200 C),
stable summer water temperatures; fertile lakes, reservoirs, and ponds (TDS
levels of 100 to 350 ppm); extensive littoral areas (~ 20% of surface area);
and moderate turbidities (25 to 100 JTU).

HSI = Number of above criteria present
5

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