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A new computer-based method is presented for the "tracing" of growth curves through fish length-frequency samples sequentially arranged in time. The method allows for an objective extraction of growth parameters whenever representative samples are available from a fish population. The method is suited both to the analysis of growth in tropical stocks and in temperate stocks, where growth oscillates seasonally.
This selection of methods is based on lecture notes used at a FAO/DANIDA training course held in Mombasa, Kenya, in May-June 1980. The methods presented are: regression and correlation, estimation of growth parameters from length-frequency data, estimation of mortalities (total, natural, fishing mortality) and analysis of catch and effort data.
A computer program is presented which allows for fitting growth curves of the von Bertalanffy type to any set of weight- or length-at-age data. The data may be weighted by sample size, need not be spaced at regular intervals, and a forcing value for the asymptotic size may be used. The goodness of fit is estimated.