habitat suitability index models and instream flow suitability curves

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Habitat variablesSuitabil ityindicesLHe regui sitesSubstrate type --------V3~,------r-r-Food/CoverPercent cover-------- V 4Trophic status-------- V ll- - - - - - - Other ------'Figure 2. Diagram illustrating habitat variables in the lacustrineHSI model and the aggregation of the corresponding suitabilityindices (Sl ls) into an HS1. HSI = the lowest of the 10 sUitabilityindex ratings.9
For explanations on why temperature (Va) and D.O. (V 1 0 ) were included inthis component, see the water quality component of the riverine HSI model.Other component. Trophi c status (V 11) was i ncl uded as a measure ofhabitat suitabi 1ity for spotted bass because ferti 1ity and mean depth havebeen identified by regression analyses and observation as variables highlylikely to affect the population abundance of spotted bass in reservoirs (seeHabitat Use Information section). A general trophic class rating system isthought to be a more representative and useful system of rating than specificSI graphs for TDS and mean depth because available information is only of ageneral nature. Deep, relatively oligotrophic reservoirs define the optimumlacustrine habitat for spotted bass. Examples of reservoirs with thesecharacteristics, and that have high standing crops of spotted bass, are:MeanReservoir/location Fertility depthCenter Hill, Tennessee TDS = 115 mg/l 24 m(MEl = 4.8)Bull Shoals, Arkansas* TDS = 150 mg/l 22 m(MEl = 6.8)*Secchi depth = 8.4 mAllatoona, Georgia TDS = 40 mg/l 10.3 m(MEl = 3.9)Lewis Smith, Alabama low 30 mClaytor, Virginia low highReferencesHargis 1965; Leidy andJenkins 1977Leidy and Jenkins 1977;Vogele 1975aKirkland 1965; Leidyand Jenkins 1977Webb and Reeves 1975Roseberry 1950In contrast, spotted bass populations do poorly in shallow, eutrophic impoundmentseven if they were common in the stream prior to impoundment (Patriarche1953; Vogele 1975a).HSI determination. The most limiting factor (i .e., lowest SI score) wasassumed to define carrying capacity for spotted bass in reservoirs; thus, HSIequals the minimum value for suitability indices V 3 through V 1 1 •Suitability Index (SI) Graphs for ModelVariablesTable 1 lists the rationale and assumptions used in constructing each SIgraph. Graphs were constructed by converting ava il abl e i nformat i on on thehabitat requi rements of spotted bass into an index of suitabil ity from 0.0(unsuitable) to 1.0 (optimum). Descriptors for each habitat variable werechosen to emphasize limiting conditions for each variable. This choicereflects our assumption that extreme, rather than average, values of a variablemost often limit the carrying capacity of a habitat. (R) refers to Riverineand (L) to Lacustrine model variables.10
Page 2 and 3: MODEL EVALVATION FORMHabitat models
Page 4 and 5: FWS/OBS-82/10.72September 1984HABIT
Page 6: PREFACEThe Habitat Suitability Inde
Page 9 and 10: ACKNOWLEDGMENTSw. G. Layher (Kansas
Page 11 and 12: Age, Growth, and FoodSpotted bass t
Page 13 and 14: Embryo. Because nests in reservoirs
Page 15 and 16: TurbidityV spH V 6Water Quality HSI
Page 17: Reproduct i on component. Spawni ng
Page 21 and 22: R,L V 4 Percent cover 1.0(boulders,
Page 23 and 24: R,L V lO Minimum dissolved 1.0oxyge
Page 25 and 26: Table 1.(continued).VariableAssumpt
Page 27 and 28: Table 1. (continued).VariableAssump
Page 29 and 30: habitat suitability for spotted bas
Page 31 and 32: for a fish species as a function of
Page 33 and 34: Category four curves (conditional p
Page 35 and 36: x0.01.0100.0x0.00.51.0100.0Coordina
Page 37 and 38: Coordinatesx 1-0.0 1.01.0 0.0100.0
Page 39 and 40: 1.0'r- 0.4.0ttl+->Coordinates>< 0.8
Page 41 and 42: 1.0x0.00.20.51.01.52.0100.0Coordina
Page 43 and 44: CoordinatesxY0.0 1.00.2 1.01.0 0.42
Page 45 and 46: Spawning depth. Vogele (l975a) obse
Page 47 and 48: Cross, F. B. 1954. Fishes of Cedar
Page 49 and 50: Mohler, H. S. 1966. Comparative sea
Page 51 and 52: 50272 '101REPORT DOCUMENTATION 1. R
Page 53: DEPARTMENT OF THE INTERIORu.s. FISH

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