Dispersion Statistics and Sample Size Estimates for Three Fish Species (Symphodus ocellatus,Serranus scriba and Diplodus annularis) in the Lavezzi Islands Marine Reserve (South Corsica,Mediterranean Sea) |
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| Authors: | David Mouillot Jean-Michel Culioli Alain Lepretre Jean-Antoine Tomasini |
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| Abstract: | For the correct management of the future International Marine Park of Bonifacio, a sampling strategy must be adopted to follow the population fluctuations of certain species of fish. This sampling will be carried out by SCUBA visual census using the fixed point method. The information to be gleaned using this method will include estimates of biomass. These data will subsequently be used to perform both spatial comparisons between sites and temporal comparisons over periods of several years. In order to reveal the existence of statistically significant differences, the sampling strategy adopted must allow accurate means to be obtained which possess relatively low coefficients of variability. The calculation of this optimum sampling depends on the spatial distribution of the species examined. The Taylor law (s2 = a ×x b), which represents a much utilized mean-variance relationship, will be used to compare the aggregation of three species of fish (Symphodus ocellatus,Serranus scriba and Diplodus annularis) on two different substrate types (Posidonia oceanica meadows and rocks) and for four sites in the Lavezzi Islands. The goodness of fit of this law to the biomass data will allow an optimum sampling strategy to be determined for each species with coefficients of variability of 10 and 25%. |
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| Keywords: | Fish biomass optimum sample size spatial distribution Taylor's power law |
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