A SPLIT-BEAM ECHO COUNTING MODEL - DEVELOPMENT OF STATISTICAL PROCEDURES

Mulligan and Kieser (1996) (ICES Journal of Marine Science, 53: 403-40 6) proposed a split-beam echo counting model that addressed the proble m of non-uniform detection probability combined with non-uniform fish density over the beam cross-section. To apply the model to real data, statistical procedures to estimate three-dimensional density functions , to estimate kernel density smoothing parameters from the data, and t o estimate a data-based smoothing parameter for kernel regression have been developed. In addition, a method to select echoes from individua l fish that have been accurately tracked by the automatic tracking alg orithm is described. The performance of the model was tested using dat a from a simulation program and from an experiment that compared acous tic estimates with visual counts of migrating salmon.