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Last modified
7/14/2009 5:02:35 PM
Creation date
5/22/2009 7:27:44 PM
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UCREFRP
UCREFRP Catalog Number
9443
Author
Bestgen, K. R., G. B. Haines, R. Brunson, T. Chart, M. Trammell, R. T. Muth, G. Birchell, K. Chrisopherson and J. M. Bundy.
Title
Status of Wild Razorback Sucker in the Green River Basin, Utah and Colorado, Determined From Basinwide Monitoring and Other Sampling Programs.
USFW Year
2002.
USFW - Doc Type
Project Number 22D,
Copyright Material
NO
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where m;,;+, is the number of fish captured in year i and i + 1, and n; and n;+, is the number of <br />fish captured in each sampling year. We estimated abundance of adult razorback suckers for all <br />pairs of years beginning in 1980 rather than using previously computed estimates from 1980 to <br />1992 because of corrections to capture histories that were discovered since the Modde et al. <br />(1996) analyses. We tested for trends in abundance over time for periods 1980-1992, 1990 to <br />1999, and the entire period (1980 to 1999) by regressing abundance estimates (as In) as a <br />function of time. No correction was made for years when no estimates were available. We <br />assumed these are the best available data, recognizing that mistakes in recording, non-detection <br />of PIT tags, and other factors may affect the capture histories used in these analyses. Future <br />efforts should ensure that accurate data recording and tag detection is a priority. <br />Survival estimates.-Jolly-Seber type models (recapture only and Barker's survival and <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br />population rate of change models) in program MARK (White and Burnham 1999) were used to <br />estimate survival rates of wild adult razorback suckers. The goal of these analyses was to <br />estimate probability of capture (p) and apparent survival rate (~) offish in the population <br />available for capture. We assumed that all individuals in the middle Green River population <br />were available for capture so that apparent survival rate ~, assuming tag loss of zero and site <br />fidelity = 1, can be considered an estimate of true survival S. The assumption of site fidelity was <br />not specifically evaluated, but can be considered so for the purposes of this analysis because <br />movement of fish in the middle Green River was thought restricted to the area encompassed by <br />our sampling (Tyus and Karp 1990). We used Barkers model to estimate lambda (7L), the <br />population rate of change, which is a joint function of survival, recruitment, and fidelity of the <br />animal to the study area. A ~, value less than one indicates a declining population, ~, > 1 <br />indicates an increasing population, and ~, =1 indicates a stable population. Global models that <br />9 <br /> <br />
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