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Autor Lang, Karen   
  Titel Die Bachmuschel Unio crassus (Philipsson, 1788) im Kinzigtal: Bestandssituation, Fortpflanzungsbiologie und Wanderverhalten Typ Zeitschrift, Artikel
  Jahr 2000 Publikation Mitt. bad. Landesver. Naturkunde u. Naturschutz Kurztitel der Zeitschrift  
  Band 17 Ausgabe 3 Seiten 541-553  
  Schlüsselwörter  
  Zusammenfassung (down) Muschel, Unio crassus, Bestand, Wanderverhalten, Ökologie, Döbel, Leuciscus cephalus, Elritze, Phoxinus phoxinus, Bachforelle, Salmo trutta fario, Fortpflanzung  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache de Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft nein  
  Rufnummer Signatur 2785  
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Autor Magnusson, K. G.   
  Titel An overview of the multispecies VPA -- theory and applications Typ Zeitschrift, Artikel
  Jahr 1995 Publikation Rev. Fish Biol. Fish Kurztitel der Zeitschrift  
  Band 5 Ausgabe 2 Seiten 195-212  
  Schlüsselwörter vpa, statistik, modell, vergleich, fischerei  
  Zusammenfassung (down) Multispecies virtual population analysis is an attempt to take species interactions into account when assessing the status of fish stocks. It was introduced primarily with the aim of lowering the uncertainty in the natural mortality rate as used in single species VPA and to take account of variability between years and ages by calculating inside the model the part of the mortality rate caused by predation. The output of the MSVPA is therefore – in addition to stock sizes and fishing mortality rates as in single species VPA and intraspecific – and possible species replacement are not considered and neither is predation on larvae and prerecruits. The potential relevance of multispecies models lies in long-term forecasts since short-term forecasts from multi- and single species models differ only slightly. In making long-term forecasts, predicting recruitment is of fundamental importance and the value of MSVPA in throwing light on the processes governing recruitment is limited. MSVPA is concerned primarily with calculating postrecruitment mortalities, and although in principle there is nothing to prevent prerecruitment predation mortalities being calculated, such estimates are not likely to be reliable or useful. Predation on the larval stages can be of major importance in determining recruitment but is not addressed in the MSVPA. Thus, it is quite possible that processes which are not dealt with in the MSVPA are much more important in determining the future of the fisheries. In view of all this uncertainty, it is inevitable that it will be questioned whether multispecies management advice is superior to single species advice.  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft  
  Rufnummer 498 Signatur 2298  
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Autor Boutillier, J.; Noakes, D.; Heritage, D.; Fulton, J.   
  Titel Use of multiattribute utility theory for designing invertebrate fisheries sampling programs Typ Zeitschrift, Artikel
  Jahr 1988 Publikation N. AM. J. FISH. MANAGE. Kurztitel der Zeitschrift  
  Band 8 Ausgabe 1 Seiten  
  Schlüsselwörter Fischerei, theorie, statistik, methode, multivariat, zusammenfassung  
  Zusammenfassung (down) Multiattribute utility theory (MAUT) and integer programming are employed to examine optimal sampling strategies for commercial invertebrate fisheries in British Columbia, Canada. Attributes considered in the study take into account various biological, economic, social, and political aspects of the fisheries. Twenty-six fishery managers, biologists, and researches from the Department of Fisheries and Oceans participated in ranking and assigning weights to each of the attributes to provide overall utility scores. Integer programming was then employed to generate optimal sampling strategies subject to various cost, personnel, are, and fishery constraints. The results clearly demonstrate the potential usefulness of MAUT analysis for developing strategies to monitor commercial invertebrate fisheries.  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft  
  Rufnummer 284 Signatur 2162  
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Autor Chen, Y.; Jackson, D. A.   
  Titel Robust estimation of mean and variance in fisheries Typ Zeitschrift, Artikel
  Jahr 1995 Publikation Trans. Am. Fish. Soc Kurztitel der Zeitschrift  
  Band 124 Ausgabe 3 Seiten 401-412  
  Schlüsselwörter fishery-statistics; population-characteristics; statistical-analysis  
  Zusammenfassung (down) Many fisheries data are commonly summarized by two statistics: mean and variance (or standard deviation). Because observed values are subject to various errors, which often are large and heterogeneous in fisheries studies, outliers commonly exist in the data. The existence of outliers biases estimation of the mean and variance if traditional estimation methods are used. Instead of assuming that errors in fisheries data follow a normal distribution with a constant variance, we propose that errors associated with observations for a variable may encompass a mixture of different levels of normally distributed errors. Based on concepts from a robust regression method, least median of squares, that is not sensitive to atypical observations in data, we develop a simple algorithm to estimate mean and standard deviation. We compare the proposed robust estimation approach with traditional methods and Tukey's biweight robust approach using simulated and field data. Based on simulations, we found little difference in estimated means and variances between the proposed and traditional methods when there were no outliers defined in simulated data. However, when outliers were defined in simulated data, the errors in estimation of the mean and its standard deviation were much smaller with the proposed method than were those estimated with traditional methods. Means and standard deviations estimated with the proposed method changed little, regardless of whether or not the simulated data were contaminated by atypical values. The proposed approach tended to have smaller estimation errors than did the robust biweight method. We demonstrate how the significance and interpretation of fisheries and ecological relationships may be adversely affected when outliers are present. We suggest using our proposed robust method to identify and down-weight outliers in estimating a mean and its standard deviation. One should justify deletion of the identified outliers using the knowledge about fish biology and environmental conditions independent of the variable assessed.  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft  
  Rufnummer Signatur 308  
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Autor Akamine, T.; Kishino, H.; Hiramatsu, K.   
  Titel Non-biased interval estimation of Leslie's removal method Typ Zeitschrift, Artikel
  Jahr 1992 Publikation Bull. Japan Sea Natl. Fish. Res. Inst. Nissuiken Hokoku Kurztitel der Zeitschrift  
  Band Ausgabe 42 Seiten 25-39  
  Schlüsselwörter Fisch, statistik, modell, binominal, population, basic, listing  
  Zusammenfassung (down) Leslie's removal method, which is used to estimate the initial population size and the removal ratio simultaneously, is modeled in terms of the product of binomial distributions. The approximation of these binomial distributions to the standard normal distribution presents a new method which has no bias for estimators. This is an improvement over the maximum likelihood method and the likelihood ratio test, and is essentially equivalent to a standard goodness-of-fit test. The confidence region on the 2-dimensional plane defined by the initial population size and the removal ratio gives each confidence interval. This region is defined by the chi-square distribution with 2 degrees of freedom.  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft nein  
  Rufnummer 452 Signatur 2256  
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Autor Akamine, T.   
  Titel An interval estimation of Leslie's method in removal methods Typ Zeitschrift, Artikel
  Jahr 1990 Publikation Bull. Japan Sea Natl. Fish. Res. Inst. Nissuiken Hokoku Kurztitel der Zeitschrift  
  Band Ausgabe 40 Seiten 27-49  
  Schlüsselwörter Fisch, statistik, binominal, population, basic, listing, modell, methode  
  Zusammenfassung (down) Leslie's method in removal methods is modeled into the joint of the binomial distributions. An interval estimation of p (removal ratio) and n (initial population size) based on the null hypothesis for p and n is easily obtained by the approximation of each binomial distribution to the normal distribution. The confidence region on the (p, n) plane is easily obtained by micro-computers. The maximum likelihood method for a point estimation and the convenient method on the curves of partial maximum likelihood for an interval estimation are also presented.  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft nein  
  Rufnummer 451 Signatur 2255  
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Autor Castro, M.; Erzini, K.   
  Titel Comparison of two length-frequency based packages for estimating growth and mortality parameters using simulated samples with varying recruitment patterns Typ Zeitschrift, Artikel
  Jahr 1988 Publikation FISH. BULL. Kurztitel der Zeitschrift  
  Band 86 Ausgabe 4 Seiten  
  Schlüsselwörter Methode, wachstum, mortalitÄt, lÄngenfrequenz, vergleich, statistik, fisch  
  Zusammenfassung (down) Length-frequency distributions were simulated for species with recruitment patterns characteristic of many tropical fish: 1) one recruitment peak per year, fast growth and very high mortality, 2) one recruitment peak per year, slow growth and moderate to high mortality 3) two recruitment peaks per year, slow growth and moderate to high mortality, and 4) random recruitment, slow growth and moderate to high mortality. Two microcomputer program packages – one incorporating the ELEFAN I & II programs and the other implementing a form of Modal Progression Analysis – were used to estimate growth and mortality parameters, and these were compared with the initial parameters used to generate the simulated samples. The results, while generally encouraging, suggest that multiple recruitments per year make it difficult to estimate growth and mortality parameters using these two packages.  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft nein  
  Rufnummer 188 Signatur 2077  
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Autor Mohn, R.   
  Titel Length-Based Virtual Population Analysis; A Review and Swordfish Example Typ Zeitschrift, Artikel
  Jahr 1991 Publikation ICCAT Working Document Kurztitel der Zeitschrift  
  Band Ausgabe Seiten  
  Schlüsselwörter Fischerei, population, cpue, lÄngenfrequenz, wachstum, modell, statistik  
  Zusammenfassung (down) 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.  
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  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft nein  
  Rufnummer 414 Signatur 2218  
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Autor Yamagishi, H.; Ishioka, K.   
  Titel Silumation Study on the Growth Variation of Fish with Special Reference to the Mortality by Cannibalism Typ Zeitschrift, Artikel
  Jahr 1991 Publikation Bull. Nansei Natl. Fish. Res. Inst. Nanseisuikenho. Kurztitel der Zeitschrift  
  Band Ausgabe 24 Seiten 163-176  
  Schlüsselwörter Wachstum, mortalitÄt, simulation, methode, theorie, statistik  
  Zusammenfassung (down) In respect to the higher initial mortality in fish by cannibalism, computer simulation of individual growth variation was made in terms of coefficient of variation(CV) and skewness(sk) of frequency distribution. CV of the cannibalistic groups changed similarly to the control groups, but converged on smaller values than the asymptotic CV of the control groups. Sk of the cannibalistic groups finally converged on similar values to those of the control groups after irregular changes in positive values except N-N correspondent type.  
  Adresse  
  Organisation Abschlussarbeit  
  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft  
  Rufnummer 217 Signatur 2105  
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Autor Akamine, T.; Matsumiya, Y.   
  Titel Mathematical analysis of age-length key method for estimating age composition from length composition Typ Zeitschrift, Artikel
  Jahr 1992 Publikation Bull. Japan Sea Fish. Res. Inst. Nissuiken Hokoku Kurztitel der Zeitschrift  
  Band Ausgabe 42 Seiten 17-24  
  Schlüsselwörter Fisch, statistik, normalverteilung, lÄngenfrequenz, theorie, methode  
  Zusammenfassung (down) In mathematics, the age-length key method is an estimating method for the ratio of each distribution in a mixture of distributions. Although the maximum likelihood method is the principle of this estimation, this model is a nonlinear model with a restrictive condition. At first, Hasselblad solved this model by using a new iteration method with a computer. Although his method was regarded as the steepest descent method or EM algorithm, it is proved to be an application of Lagrange's indeterminate multiplier method to the iteration method. Nowadays, there are other useful algorithms of optimization, especially Marquardt's method, for this estimation.  
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  Herausgeber Erscheinungsort Editor  
  Sprache Sprache der Zusammenfassung Originaltitel  
  Editor der Reihe Titel der Reihe Kurztitel der Reihe  
  Band der Reihe Ausgabe der Reihe Edition  
  ISSN ISBN Medium  
  Bereich Expedition Konferenz  
  Notizen Geprüft nein  
  Rufnummer 454 Signatur 2258  
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