COMPARISON OF THE NOVEL INVERSE TECHNIQUES FOR FISH TARGET STRENGTH ESTIMATION

摘要

The state of the art. 'in situ' indirect methods of fish target strength (TS) estimation are analysed in terms of the inverse techniques recently applied to the problem in question. The solution of the problem is obtained by solving the integral equation, relating PDF's of echo variable, target strength and beam pattern of the echo sounder transducer. The novel TS-estimation methods, viz.: Expectation, Maximization and Smoothing (EMS), Windowed Singular Value Decomposition (WSVD), Regularization and Wavelet Analysis are presented and compared. The obtained estimates are superior of those obtained from deconvolution or other conventional techniques, as the analyzed methods partly avoid the problems of ill-conditioned equations and matrix inversion.