Schweigert, J. F. (1991). Multivariate Description of Pacipic Herring (clupea Harengus p.) Stocks from Size and Age Information (Vol. 48).
Schlüsselwörter: Fischerei, statistik, multivariat, genetik, morphologie, methode
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France, R., Holmes, J., & Lynch, A. (1991). Use of size-frequency data to estimate the age composition of crayfish populations (Vol. 48).
Zusammenfassung: Age-classes in crayfish populations can be determined from size-frequency data provided 4 tents are adhered to only crayfish collected from areas of rock substrate are used; trapping are excluded; species do not have longevities exceeding about 4 yr; and most importantly, sample sizes are greater than about 200. Studies that have failed to follow these guidelines have met with limited success in dissecting mixed frequency distributions. Further, 3 validation procedures must be undertaken: temporal replication within molting events to measure the precision of both data collection and size-frequency analysis; corroboration with known-age crayfish from either field recaptures or laboratory molt increments; and concordance with independent analysis of the mean size at onset of sexual maturity. When these checks support the size-frequency results, population age composition and analyses of rates of growth or mortality can be considered reliable.
Schlüsselwörter: Krebs, lÄngenfrequenz, methode, statistik, population
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(1991). ObjectWindows für C++.
Schlüsselwörter: Dokumentation, tips
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Murphy, B. R., Willis, D. W., & Springer, T. A. (1991). The Relative Weight Index in Fisheries Management: Status and Needs (Vol. 16).
Schlüsselwörter: Fischerei, statistik, wachstum, modell
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Stal, M. (1991). Systeminterna nach INI-Art.
Schlüsselwörter: Windows, tips
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Sekine, M., Nakanishi, H., Ukita, M., & Murakami, S. (1991). A shallow-sea ecological model using an object-oriented programming language (Vol. 57).
Zusammenfassung: The purpose of this study is to construct a model that can predict the impact on fisheries caused by coastal development activities. To accomplish this, many species of fish must be incorporated in the model, because each type of fish has a different value as a fishery resource and a different behavior for the same impact. In addition the effect of fish swimming must be considered because even when the total resource amount of fish does not change, fish may still disappear from the object area. These factors make the model structure complicated. Meanwhile, a new concept called “object oriented programming” (OOP) is attracting the attention of modellers. In this paper, we have constructed a model called the “shallow-sea ecological model” (SSEM), by using Smalltalk, which is representative of the OOP language. This showed that the fishing ground environment are expressed very flexibly and plainly by Smalltalk.
Schlüsselwörter: Ökosystem, modell, oop, methode, theorie
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Mohn, R. (1991). Length-Based Virtual Population Analysis; A Review and Swordfish Example.
Zusammenfassung: Length-based population analyses have had a fairly long but not too successful history. These methods are required over a range of situations from when aging is impossible to when it is difficult or prohibitively expensive. There have been 3 sorts of approaches: 1) modal analysis to convert length frequencies to ages 2) age-length key enhancement and 3) imbedded growth models. The last group is what is generally known as length-based methods and the focus of this review. At the 1991 ICES Methods Working Group, 5 techniques were compared and these results are summarized. Two of these techniques, cohort slicing and length-based ADAPT, are applied to swordfish (Xiphias gladius ) data. The imbedded growth model for the former technique is the mean size at age while the latter uses the distribution of size at age. A new method is also presented which begins with cohort slicing then estimates numbers at age and enhances an inferred age-length key at each step of an iterative process.
Schlüsselwörter: Fischerei, population, cpue, lÄngenfrequenz, wachstum, modell, statistik
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Ganguly, S., & Chaudhuri, K. (1991). A note on an extension of Schaefer's model (Vol. 55).
Zusammenfassung: Schaefer's model on the exploitation of a single species fish community obeying the logistic law of growth has been modified by adopting an alternative functional form for the harvest rate. The stability of the nontrivial steady state is discussed. The existence of a bionomic equilibrium is proved. The problem for optimal exploitation of the fishery is studied by using variational calculus. Some results are numerically computed to make a comparative study of Schaefer's model and the present one.
Schlüsselwörter: Statistik, population, modell, algorithmus
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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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Zerrath, H. (1991). Sprintleistungen einheimischer Klein- und Jungfische in Sohlgleitenmodellen-Daten zur Bewertung von Fischaufstiegsanlagen. Diploma thesis, , .
Schlüsselwörter: Fisch, Sohlgleitenmodell, Fischaufstiegsanlage
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