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Bagliniére, E., & Ombredane, D. (1990). Choix et fibilité d'un modéle de rétrocalcul des tailles en écologie halieutique, mise au point d'un logiciel informatique (Vol. 319).
Schlüsselwörter: Fischerei, population, modell, statistik, Grundlage
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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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Hilge, V. (1990). Beobachtungen zur Aufzucht von Zandern (Stizostedion lucioperca L.) im Labor (Vol. 40).
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Negele, R. - D., Leuner, E., Bohl, E., & Leyerer, R. (1990). Ökoparasitologische Untersuchungen an Fischen des Königssees, Obersees und Grünsee (Vol. 21).
Schlüsselwörter: Fisch, Parasit, Cestoda, Trematoda, Nematoda, Acanthocephala, Protozoa, Zwischenwirt
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Gebhardt, H. (1990). Die Bedeutung des Inundationsgebietes des Rheins als Laichgebiet für Fische (Vol. 1).
Schlüsselwörter: Fisch, Fortpflanzung, Rhein
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Müller, R. (1990). Vorläufige Mitteilungen zur Fischfauna des Bezirkes Suhl (Vol. 5).
Schlüsselwörter: Fisch, Vorkommen
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Köhler, C., & Müller, A. (1990). Statistische Untersuchungen zum Längen-Gewichtsverhältnis ausgewählter Fischarten aus dem Rhein (Vol. 2).
Schlüsselwörter: Längen-Gewichtsverhältnis, Fisch, Rhein
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Michelbach, S. (1990). Vergleichende Untersuchung von Groppen-Populationen (Cottus gobio) der Tauber und ihrer Nebenbäche, von Jagst und Kocher (Vol. 9).
Schlüsselwörter: Fisch, Groppe, Cottus gobio, Vorkommen
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He, X. (1990). Effects of predation on a fish community: A whole lake experiment.
Zusammenfassung: Studies of predator-prey interactions have been limited to laboratories or relatively small scale field experiments because of logistic difficulties in large scale field experiments. Much evidence has suggested that predictions based on small scale experiments on predator-prey interactions may not be simply extended to large scales, e.g. whole system. This study was designed to examine predation effects on a prey fish assemblage at the whole lake scale. After a year of premanipulation study, northern pike (Esox lucius) were introduced into a small piscivore-free lake inhabited by 14 species of fishes. In the third and fourth years, the lake was divided by a large mesh fence and northern pike were introduced into one half of the lake. Predation effects on individual prey population were estimated for both direct effects (i.e., consumption of prey species) and indirect effects, including habitat changes associated with predator avoidance behavior, increase of emigration rates and changes of population size structure. The relative importance of direct versus indirect effects was examined using randomized intervention analysis along with a model that quantifies the indirect effects. Decreases of prey fish biomass due to increased emigration was at least as great as that due to the direct effect of consumption when prey biomass was high (>40 kg/ha) but not when prey biomass was low (<30 kg/ha). Significant indirect effects included dramatically decreased abundance of the dominant species (northern redbelly dace, Phoxinus eos), increase of some rare species (sunfish, Lepomis spp. and creek chub, Semotilus atromaculatus), and decreased mean sizes of redbelly dace. Indirect effects occurred rapidly and were most apparent immediately following the introduction of northern pike. Community responses to northern pike predation included changes of species composition, species diversity and community stabilities. The fish communities were significantly different among the pre-pike period, pike period and post-pike period. The greatest variance was related to abundances of redbelly dace and sunfish. However, predation effects on the prey fish community depended on the observational scales used to determine community structure. (DBO)
Schlüsselwörter: predation-; interspecific-relationships; freshwater-fish; population-dynamics; Esox-lucius; Phoninus-eos; Lepomis-; Semotilus-atromaculatus; freshwater-ecology
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Millar, R. B. (1990). A versatile computer program for mixed stock fishery composition estimation. Department of Fisheries and Oceans, St. John's, Nfld. (Canada).
Zusammenfassung: This technical report describes a FORTRAN program (HISEA.FOR) to be used in the study of mixed stock fishery composition estimation. Program HISEA is a versatile research tool capable of performing analyses. The simplest use of HISEA is to perform a composition analysis. The program can then be run in bootstrap mode to provide a non-parametric estimate of the reliability of the estimated compositions. In simulation mode, HISEA can quantify the effect of changing sample sizes; of adding or removing variables; and of adding or removing stocks. Simulation also identifies potential problems (such as high bias and variance in the composition estimators) that may arise due to different stocks being too alike.
Schlüsselwörter: check-lists; approximation-; computer-programmes; stock-assessment
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