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Last modified
8/11/2009 11:32:56 AM
Creation date
8/10/2009 3:53:19 PM
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UCREFRP
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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<br />t <br /> <br />Embryo. Optimal temperature for spawning and subsequent development <br />ranges from 20 to 270 C (Childers 1967). Spawning will not occur below 190 C <br />or above 310 C (Hunter 1963). Optimal spawning substrate corresponds to a <br />predominance (~ 50%) of sand and gravel (Hankinson 1919; Hunter 1963; Childers <br />1967). Green sunfi sh spawn at depths of 4 to 35 cm (Hunter 1963; Carson <br />1968); consequently, reservoir drawdown should not exceed 1 m during spawning <br />to ensure optimal embryo development and survival. Probability of use curves <br />developed by Hardin and Bovee (1978) illustrate that optimal current velocity <br />is S 10 cm/sec, and embryos probably will not tolerate velocities> 15 cm/sec. <br /> <br />Fry. Optimal temperatures for fry range from 18 to 260 C (Siewert 1973; <br />Coutant 1977; Hardin and Bovee 1978). The range of tolerance for bluegill fry <br />is 10 to 360 C (Banner and Van Arman 1972), and it is assumed that green <br />sunfish fry tolerances are similar. Optimal current velocities are S 5 cm/sec, <br />and fry avoid areas with velocities exceeding 8 cm/sec (Kallemyn and Novotny <br />1977; Hardin and Bovee 1978). <br /> <br />Juvenile. Specific requirements for juveniles are assumed to be the same <br />as those for the adult life stage. <br /> <br />HABITAT SUITABILITY INDEX (HSI) MODELS <br /> <br />Model Applicability <br /> <br />t Geographic area. The models are applicable throughout the native and <br />introduced range of ~he green sunfi shi n North America. The standard of <br />comparison for each individual variable suitability index is the optimal value <br />of the vari ab 1 e that occurs anywhere withi n thi s regi on. Therefore, the <br />models will never provide an HSI of 1.0 when applied to bodies of water in the <br />North where temperature related variables do not reach the optimal values that <br />occur in the South. <br /> <br />Season. The models provi de a rating for a body of water based on its <br />ability to support a reproducing population of green sunfish during all seasons <br />of the year. <br /> <br />Cover types. The models are applicable in riverine, lacustrine, <br />palustrine, and estuarine habitats, as described by Cowardin et ale (1979). <br /> <br />Minimum habitat area. Minimum habitat area is defined as the minimum <br />area of contiguous suitable habitat that is required for a species to live and <br />reproduce. No attempt has been made to establish a minimum habitat size for <br />green sunfish. <br /> <br />Verification level. The acceptable output of these green sunfish models <br />is to produce an index between 0 and 1 which the authors believe has a posi- <br />tive relationship to carrying capacity. Acceptance was based on model predic- <br />tions using sample data sets. These sample data sets and their relationship <br />to model veri.fication are discussed in greater detail following presentation <br />of the mode 1 . <br /> <br />t <br /> <br />3 <br />
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