PATCHY DISTRIBUTION FIELDS - SURVEY DESIGN AND ADEQUACY OF RECONSTRUCTION

A mathematical model (Kriging) was used to examine the effects of acou stic survey design on the adequacy of reconstruction of patchy distrib ution fields. The model simulates fish (or plankton) patches of differ ent shapes and spatial orientations, and an acoustic survey by paralle l transects. For a series of mathematical experiments, the patchy fiel ds were reconstructed using simulated survey data. Conformity of the r econstructed fields to those originally generated was evaluated by cal culating their correlations. The experiments indicate that a survey in the direction of patch elongation gives best results. The optimal rat io of the distance between transects to the autocorrelation radius for the field in the direction of surveying has been determined. Lack of a priori information on patch orientation may considerably reduce the quality of survey design. A posteriori determination of patch orientat ion allows reconstruction of the best field, attainable on the basis o f the data From the survey conducted. In addition, surveys of moving p atches are considered. (C) 1997 International Council for the Explorat ion of the Sea.