Scale radius growth versus standard length growth in some fish species
2005
Szypula, J. (Szczecin Agricultural University (Poland). Dept. of Fish Biology), E-mail: [email protected]
The growth of the scale radius was followed in seven fish species (roach, bream, rudd, humped rockcod, perch, halibut, and zander). The results obtained by analysing a total of 11304 individuals were compared with corresponding data on the standard length growth of each species. The mathematical description of growth was done with the following six models: the von Bertalanffy equation, the Ford-Walford formula, the second order polynomial, the Gompertz model, the power function, and the modified power function. Data on length growth and length growth versus scale radius growth, which were used to determine the scale radius growth of each species, were taken from the literature. The growth of both the scale radius and body length of the species analysed was fairly uniform: the increment ratios, averaged for the entire growth period, were close to 0.9. However, slightly higher values, hence more uniform growth, were recorded in radius growth (0.93) than in fish length growth (0.90). The fish length increments in the first two years of life were lower than the scale radius increments during the same time
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