Laserfiche WebLink
<br />Presentation to AMWG of Results of <br />an Independent Review of Methods <br />Used to Assess Status and Trend of <br />Humpback Chub <br /> <br />Concepts and Definitions <br />Population Parameters of Primary Interest <br /> <br />N = population size of adults <br /> <br />I. Concepts and definitions <br /> <br />II. Assessment of current methods, etc. <br /> <br />T = trend in population size over 5 <br />years <br /> <br />III. Recommendations <br /> <br />Concepts and Definitions <br />Population Closure <br /> <br /> <br />Geographic closure: <br />- N is defined with respect to a spatially explicit <br />geographic area, 6.g., the population within the <br />sampled boundaries of Black Rocks Canyon <br /> <br />Demographic closure: <br />- During the time period of sampling in a given year, <br />N is constant <br /> <br />Concepts and Definitions <br />Capture-recapture Estimation Models <br /> <br />Concepts and Definitions <br />Capture-recapture Estimation Models <br /> <br />Closed: <br />- Assumes geographic and demographic dosure <br />. Basic relationship is N=CI p <br />. Givell adequate data. models are good at identifying <br />sources 01 variation in p due to heterogeneity in capbJre <br />among fish or behavioral response to first caplufe <br />(CAPTURE) <br />. Sampling time frame is short relative to life history 01 <br />HOC. Le_. weeks or a lew months <br />. Multiple sampling occasions in a relativ$ly short time <br />.~ <br /> <br />Open: <br />- Assumes geographic closure <br />- Relaxes demographic closure among years <br />. Allows immigration and..bf mortality/emigration during the <br />study (Jolly-Seber Age Models. ASMA) <br />. Can additionally estimate Trend, mortality/emigralioo rate, <br />lmmtgration rale <br />. Requires more data because models haw more <br />paramelers <br />. Accommodales longer time frames (years) <br />. Classic applicatiOn assumes a single sampling occasion <br />per year <br />. Generally cannol handle variatiOn in p within years, <br />whiCh causes bias In estimatiOn of N <br /> <br />02302 <br />