Zusammenfassung: The paper describes methods of estimating population size based on survey removal data. The Zippin maximum likelihood model is presented with the possibility with microcomputer. The Carle and Strub method is considered most convenient and a microcomputer program is published.

Zusammenfassung: This paper describes a method and a FORTRAN program for the estimation of von Bertalanffy growth parameters, total mortality rates and gear selection/recruitment parameters from a time series of length-frequency samples weighted by catch per effort (e.g., numbers caught per hour by length class each quarter of the year). The length frequencies are separated into normally distributed components each of which represents a cohort. This method is constructed to allow for continuous, seasonally variable recruitment all year-round and is intended to be used especially for tropical and other fish stocks displaying an appropriate recruitment pattern.