Patchy distribution fields: survey design and adequacy of reconstruction

Abstract

A mathematical model (Kriging) was used to examine the effects of acoustic survey design on the adequacy of reconstruction of patchy distribution fields. The model simulates fish (or plankton) patches of different shapes and spatial orientations, and an acoustic survey by parallel transects. For a series of mathematical experiments, the patchy fields were reconstructed using simulated survey data. Conformity of the reconstructed fields to those originally generated was evaluated by calculating their correlations. The experiments indicate that a survey in the direction of patch elongation gives best results. The optimal ratio 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 orientation allows reconstruction of the best field, attainable on the basis of the data from the survey conducted. In addition, surveys of moving patches are considered.