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Last modified
7/14/2009 5:02:36 PM
Creation date
5/17/2009 10:58:57 PM
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UCREFRP
UCREFRP Catalog Number
9560
Author
Valdez, R. A.
Title
A Generalized Interactive Model to Predict Floodplain Habitat Area Needed to Recover the Endangered Razorback Sucker in the Upper Colorado River Basin - Floodplain Model Version 5.1.
USFW Year
2004.
USFW - Doc Type
Logan, UT.
Copyright Material
NO
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<br />VI <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />life history of the species, including initial population size, sex ratio, average total length (TL) of <br />females, percent hatching success, percent larval emergence, survival of larvae during drift, <br />entrainment rate of larvae in floodplains at various river miles, time spent in floodplains, monthly <br />survival in floodplains and annual survival in the mainstem, and fish density. The model allows <br />for any of the input variables to be changed with instant automated output. Output variables <br />include intermediate computations, such as number of females based on initial number of adults <br />and sex ratio, average fish weight, number of eggs produced, number of larvae emerging, number <br />of larvae entrained, and number offish surviving in floodplains. Output variables also include <br />computations of total acres and hectares of floodplains necessary to support specified densities of <br />fish, number of fish recruiting to maturity at 400 rom TL, and recruitment rate as a percentage of. <br />the initial adult population. Three figures in the model provide graphic illustration of the effects <br />of variable inputs on floodplain area, number of adults recruiting, and recruitment rate. <br />The worksheet "Drift" is a sub-model that allows the user to detennine the percentage of <br />larval drift that is entrained in floodplains, based on a mile-by-mile specification of entrainment <br />rate. Results of the Drift sub-model are used to finish running the FLOODPLAIN model. The <br />worksheet "SiteSurv" allows the user to specify different survival rates in each of 14 actual <br />floodplains located along the Green River. The worksheet "Sensitivity" contains four scenarios <br />and 17 tests of the input variables in the model that provide insight into the most sensitive <br />variables (i.e., those that have the greatest effect on output with the smallest change), as well as <br />the inter-relationships of the variables. Seven spreadsheets with charts provide a visual <br />representation and formulas of the mathematical relationships used in the model, including <br />length-weight relationship, fish weight to fecundity relationship, larval entrainment, survival of <br />drifting larvae, survival in floodplains, V on Bertalanfy growth curves, early age growth rates, and <br />later age growth rates. The worksheet "Data Sources" identifies sources of data used in the model. <br />Results of Model Runs <br />Model runs indicate that for a given set of input variables, total floodplain area necessary <br />to support a population of 5,800 adult razorback sucker at an annual recruitment rate of 0.30 <br />(Recovery Goals target population) ranges from about 78 to 3,068 acres, depending on fish <br />growth rate and density; i.e., at highest growth rate and lowest fish density, total area required to <br /> <br />
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