Titlebook: On the Dynamics of Exploited Fish Populations; Raymond J. H. Beverton,Sidney J. Holt Book 1993 Springer Science+Business Media Dordrecht 1

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Adaptation of the Simple Model to Give Other Characteristics of the Catch and Populationonomic aspect it is necessary to know the catch per unit effort, and, probably, the mean weight of fish in the catch, while the analysis of situations in which factors such as natural mortality and growth vary with the population density (discussed in Part II of this paper) requires expressions givi

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健忘症

Natural Mortalitythe scarcity of information relating to the causes of natural death in adult marine fish. Predation is perhaps the most general ‘external’ cause, and the evidence has been reviewed by Errington (1946). The majority of recorded instances of predation refer to lake or river fish, but even here, direct

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Growth and Feedingattern defined by a mathematical expression the parameters of which have constant values. In this section we are concerned with the variation of growth (i.e. in the pattern of variation of weight with age) with age itself (§9.2), among the individuals comprising a given year-class (§9.3) and with po

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Relative Fishing Power of Vessels and Standardisation of Commercial Statistics of Fishing Effortrequisite for the estimation of mortality coefficients from age-composition data and from marking experiments in all but the simplest cases, and is an essential part of the methods described in §14.3 for obtaining separate estimates of the fishing and natural mortality coefficients. When using data

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Estimation of the Total Mortality Coefficient (, + ,), and the Maximum Age, ,,ained by many authors from data of the abundance, either relative or absolute, of different age-groups. The method used has usually been the direct one of obtaining either the ratio of the abundance or total catch of a year-class during successive years of life, or the ratio of the relative abundanc

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Separate Estimation of Fishing and Natural Mortality Coefficientsortality coefficients. As we have mentioned in the previous section, the detailed analysis of mortality requires certain information in addition to that obtained from age-composition data, and we have found it convenient to classify the methods of the present section according to the type of this ad