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Nunney, L. (1991). The influence of age structure and fecundity on effective population size (Vol. 1991).
Schlüsselwörter: Population, Biologie, Theorie, Poisson
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Husband, B. C., & Barrett, S. C. H. (1995). Estimating effective Population Size: A Reply to Nunney (Vol. 49).
Schlüsselwörter: Population, Biologie, Theorie, Methode
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Hightower, J. E., & Gilbert, R. J. (1984). Using Jolly-Seber Model to Estimate Population Size, Mortality and Recruitment for a Reservoir Fish Population (Vol. 113).
Schlüsselwörter: Fisch, mark-recapt, Jolly-Seber, Mortalität, Population
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Elliott, J. M., & Hurley, M. A. (1995). The functional relationship between body size and growth rate in fish (Vol. 9).
Schlüsselwörter: Fisch, Wachstum, Modell, Statistik
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Chan, C. - L., Hoenig, J. M., Dawe, E. G., Brownie, C., & Pollock, K. H. (1995). An Efficient Design for Index-Removal and Change-in-Ratio Estimation of Population Size and Related Parameters. ICES C.M.
Schlüsselwörter: Fisch, mark-recapt, Methode, Statistik, Zippin, Mathematik
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Hoenig, J. M., Morgan, M. J., & Brown, C. A. (1995). Analysing differences between two age determination methods by tests of symmetry (Vol. 52).
Zusammenfassung: A common problem in fisheries science is the comparison of two methods for obtaining ages of individual animals. The authors suggest that if the overall level of agreement is low between two ageing methods used on the same sample of fish, then one can use a test of symmetry to look for evidence of systematic disagreement. A chi super(2) test is used to determine if the number of fish assigned age i from method 1 and age j from method 2 differs significantly from the number of fish assigned age j from method 1 and age i from method 2. Such a test can also be used to determine the range of nominal ages over which two methods appear to give comparable results.
Schlüsselwörter: Altersbestimmung, Fischerei, Statistik, Methode
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Arnason, A. N., & Mills, K. H. (1987). Detection of handling mortality and its effects on Jolly-Seber estimates for mark-recapture experiments (Vol. 44).
Zusammenfassung: Handling mortality occurs in mark-recapture experiments if animals handled and released in a given sample have a higher mortality rate than animals that were alive but not sampled. This violates the assumption of equal survival required for forming the Jolly-Seber estimates of population abundance, survival, and recruitment. The authors show that handling mortality can produce very large biases in these estimates, and we develop a test to detect it. They investigate the power of this test and find that quite large biases can be produced at handling mortality rates that are too low to be detected. They also recommend methods to prevent handling mortality from occurring in fish sampling experiments and methods to reduce bias in the estimates. The test and the bias corrections are applied to mark-recapture data for a lake whitefish (Coregonus clupeaformis ) population and to data from simulated mark-recapture experiment.
Schlüsselwörter: Fischerei, Statistik, Mathematik, Modell, Mortalität, Jolly-Seber
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Francis, R. I. C. C. (1990). Back-calculation of fish length: A critical review (Vol. 36).
Zusammenfassung: A review is made of the literature on the back-calculation of fish body length from marks on scales or other hard parts (otoliths, vertebrae, fin rays, etc.). Though the technique is widely used it does not appear to be well understood. Regression methods are commonly used, apparently in ignorance of the more realistic proportional methods. It is not generally recognized that there are two equally plausible back-calculation hypotheses which can lead to significantly different back-calculated lengths. The Fraser-Lee equation, the most commonly used back-calculated formula, follows neither of these hypotheses but is based on a misuse of linear regression. It is recommended that back-calculation be restricted to procedures following one of the proportional hypotheses; that the difference between lengths calculated using the two hypotheses is a useful measure of the minimum uncertainty in back-calculation lengths; and that more attention be paid to validating back-calculation hypotheses by comparing observed and back-calculated lengths for individual fish. The pattern of heteroscedasticity in body length-scale radius plots is noted as a useful diagnostic in evaluating back-calculation hypothesis.
Schlüsselwörter: Fisch, Statistik, Regression, Längen..., Review, Wachstum
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Swain, D. P., & Sinclair, A. F. (1994). Fish distribution and catchability: What is the appropriate measure of distribution? (Vol. 51).
Zusammenfassung: The authors show that spatially uniform changes in abundance can affect catchability given certain models for the distribution of fishing effort, but that this effect is slight compared with the effect of changes in the spatial spread of fish distribution. An index of distribution is described that depends only on spatial spread: the minimum area over which a specified percentage of the population is spread. We tested the density dependence of this index using data on Atlantic cod (Gadus morhua) in the southern Gulf of St. Lawrence. Results depended on the percentage of the population for which the index was evaluated. The area containing most (90 or 95%) of the population was density dependent, expanding as population size increased. The area of highest cod concentration (i.e., the area containing 50% of the population) did not expand significantly as population size increased.
Schlüsselwörter: Fisch, Statistik, Population, Fischerei, Geographisch, Mathematik, Modell
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Myers, R. A., & Cadigan, N. G. (1995). Statistical analysis of catch-at-age data with correlated errors (Vol. 52).
Zusammenfassung: The statistical model used is extended to estimate abundance from commercial catch-at-age data for many of the major commercial fish species in the world. The model combines commercial catch-at-age data and research survey estimates of fish abundance; extends the model to allow correlated errors among ages within a year for the survey estimates of fish abundance. Method is formulated for modeling the fishing mortality on the oldest ages of the fish caught. Estimates are obtained using maximum likelihood. The level of correlation among ages is sufficiently large to produce large biases in the standard methods for some stocks. The statistical model that includes correlated errors greatly reduces bias and increases efficiency if the correlation in the estimation error is large.
Schlüsselwörter: Fisch, Fischerei, Statistik, Wachstum, Mortalität, VPA, Population, Mathematik, Modell
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