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(1904). Die Störfischerei bei Glückstadt (Vol. 7).
Zusammenfassung: [...], die seit einiger Zeit wieder aufgenommen wurde, ist bis jetzt ohne Erfolg gewesen. Dieser einst so lohnende Erwerbszweig der Fischer geht überhaupt von Jahr zu Jahr immer mehr zurück, und demzufolge nimmt auch die Zahl der Störfischer fortwährend ab. Während z.B. vor etwa 40 Jahren von Neuendeich allein gegen 50 Störfischer dem Fang oblagen, beträgt die Zahl in diesem Jahr nur 4. Obwohl früher des reichen Fangs wegen der Preis der Störe nur 5 bis 8 Mk. für Milchner und 30 bis 40 Mk. für Rogner betrug, wurden in der Hauptsaison nicht selten Monatseinnahmen von 600 bis 700 Mk. erzielt. Mit dem Seltenerwerden dieses beliebten Fisches ging die Preiserhöhung Hand in Hand. Jetzt zahlt man 25 bis 30 resp. 175 bis 200 Mk. pro Tier.
Schlüsselwörter: Fisch, Stör, Acipenser sturio
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(1914). Gefährdung der Fischerei in der Unterelbe (Vol. 6).
Zusammenfassung: [...] Elbregulierungsarbeiten machen sich für die Stell- und Treibnetzfischerei immer schädigender bemerkbar. [...] In der Süderelbe vor der Estemündung bis Hanöfersand [...] sind Schnepel und Näse sehr viel besser genährt als elbabwärts [...] Der Rückgang von Schnepel, Näse, Aland und Maifisch u.a.m. ist hauptsächlich durch Überfischung herbeigeführt. In der Elbe sind nur noch 4 Fischarten, die das Rückgrat sämtlicher Fischerein der Unterelbe bilden, diese sind Aal, Butt, Stint und Stör [...]
Schlüsselwörter: Fisch, Fischerei, Elbe
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(1904). Fangergebnisse der unterelbischen Fischerei (Vol. 7).
Zusammenfassung: Über die Fangergebnisse der unterelbischen Fischerei im Jahre 1903 machte der 'Deutsche Seefischerei-Verein' bemerkenswerte Mitteilungen [...]Quappen wurden fast gar nicht gefangen, [...] Der Schnäpelfang, der sich elbaufwärts nur bis zur Mündung der Oste erstreckt, war unbefriedigend; insgesamt wurden 130 Stiege gefangen [...] Lachs, Lachsforellen, [...] , Maifisch [...] wurden viel angebracht und gut bewertet [...] Der Störfang war bedeutend besser als im Vorjahre, in der Oste und Stör dagegen ließ er zu wünschen übrig. Im ganzen sind 1322 Stück gefangen. Hummer sind in großer Menge, Aale und Neunaugen fast gar nicht gefangen worden.
Schlüsselwörter: Fisch, Fischerei, Elbe
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Yamagishi, H., & Ishioka, K. (1989). Simulation study on the growth variation of fish with special reference to the sexual dimorphism in growth.
Zusammenfassung: With respect to the sexual dimorphism in growth of fish, computer simulation of individual growth variation was made in terms of coefficient of variation (CV) and skewness (sk) of frequency distribution. Normal distributions of initial body length, specific growth rate in exponential growth coefficient in asymptotic growth and asymptotic value (each consisting of 500 monosexual distributions) were supposed. In exponential growth both CV and sk of the bisexual distributions increased more quickly than the two monosexual distributions. In asymptotic growth (Bertalanffy and Logistic) CV of the bisexual distribution was always greater than the monosexual distributions, and sk of the former was greater in positive value and smaller in negative value than those of the latter all the time.
Schlüsselwörter: Sex, wachstum, simulation, methode, theorie, mathematik, statistik
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Akamine, T. (1988). Evaluation of Error Caused by Histogram on Estimation of Parameters for a Mixture of Normal Distributions.
Zusammenfassung: When histograms are used instead of raw data to estimate parameters by the maximum likelihood method, data has an error distributed according to a regular distribution among the width of the histogram. This influence on the estimation of parameters is evaluated by the linearized error propagation rule. Covariance is in proportion to the width squared and in inverse proportion to the number of data. Even if the number of data is large, the precision is low for small normal distributions. In practice, an adequate width will be given by the shapes of the histograms.
Schlüsselwörter: Normalverteilung, basic, listing, methode, algorithmus, poly-verteilung
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Chen, Y., Jackson, D. A., & Harvey, H. H. (1992). A comparison of von Bertalanffy and polynomial functions in modelling fish growth data (Vol. 49).
Zusammenfassung: We compared the von Bertalanffy growth function (VBGF) and five polynormial functions (PF) in modelling fish growth for 16 populations comprising six species of freshwater fishes. Ranked results of the variance explained by each growth function indicated that VBGF described growth data better than three- and four-parameter polynomial functions. Log-transforming length and age greatly improved the goodness-of-fit of the three-parameter polynomial function. Statistical comparison of growth between populations or sexes was done using a general linear model for polynomial functions. The VBGF proved to be the best growth model for all 16 populations.
Schlüsselwörter: Fischerei, wachstum, methode, theorie, modell, statistik
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Silvert, W. (1996). Size-aggregation in models of aquatic ecosystems (Vol. 183).
Zusammenfassung: Very simple modells of pelagic marine and freshwater ecosystems have proved very successful and are increasingly widely used. These models are highly aggregated and based in biomass or particle size. Theoretical investigations based primarily on energy flow considerations have provided of the success of these models ans suggest possible ways to extend their applicability.
Schlüsselwörter: Ökosystem, Modell, Mathematik, Statistik
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Soriano, M., Moreau, J., Hoenig, J. M., & Pauly, D. (1992). New functions for the analysis of two-phase growth of juvenile and adult fishes, with application to Nile perch (Vol. 121).
Zusammenfassung: Two phases of growth can sometimes be distinguished in long-lived fish species. The first involves the growth of zooplankton-feeding juveniles and young adults. The second consists of accelerated growth of large, piscivorous adults. We present modified versions of the von Bertalanffy growth equation that account for this feature and fit them to length-at-age data on Nile perch Lates niloticus (Centropomidae) from Lake Chad (north and south) in north-central Africa, and from Lake Nasser in Egypt. The growth parameters estimated for the new equations allow one to make preliminary estimates of the energy gains by Nile perch associated with transition from zooplanktivory to piscivory.
Schlüsselwörter: Fischerei, wachstum, theorie, modell
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Clay, D. (1990). TUNE: A series of fish stock assessment computer programs written in FORTRAN for microcomputers (MS DOS) (Vol. 32).
Zusammenfassung: This set of computer programs for stock assessment uses MS FORTRAN 77 version 4.1* for all the programs. The programs will compile under version 3.2 of MS FORTRAN 77, however the Open statements with file types “Unknown” must be changed to “New” or “Old” depending on the expected status of the file. The “shell” called TUNE is used to build the appropriate batch file for submission of the multiple runs used for calibration. Each of these programs is an interactive stand alone module, each can be used independently of the others. This report gives an outline of how and where these programs fit into an analytical process. A set of disks with the source code and the executable (*.EXE) files is available from the editor or the programs can be copied from the ICCAT Secretariat in Madrid; an Annex to this report containing a listing of the source code is also available. A glossary of terms commonly used in the assessment process is presented in Appendix I.
Schlüsselwörter: computer-programmes; system-analysis; ICCAT-
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Shoesmith, E. (1990). A comparison of methods for estimating mean fecundity (Vol. 36).
Zusammenfassung: This paper is concerned with certain computational aspects of estimating the mean fecundity of a single age-class of a population of fish. Four computational methods for estimating mean fecundity are compared by Monte Carlo simulation. One of the four methods is the simple expedient of estimating fecundity at sample mean length, a method known to be downwardly biased. The Monte Carlo study shows that the other three methods reduce bias and provide worthwhile efficiency gains. For small samples, the most efficient of the four methods is a “bias adjustment”, proposed here, that uses easily calculated sample statistics. For large samples, a numerical integration method has the highest efficiency. The fourth method, a “direct summation” procedure which can be done easily in many statistical or spreadsheet programs, performs well for all sample sizes.
Schlüsselwörter: LÄngenfrequenz, normalverteilung, methode, theorie, mathematik, vergleich, statistik
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