Instantaneous separable VPA (ISVPA)

The approach suggested is in the class of cohort methods; it is a new technique for processing catch-at-age data on species having short (within a year) periods of fishery. The method can also be regarded as an approximation to more general conditions when fishery varies continuously during the year. In many cases it enables a more complete extraction of information on exploited populations and fishery from the catch-at-age matrices, including the natural mortality coefficient and terminal fishing parameters, without using any auxiliary data (survey data, fishing effort series etc.). A number of numerical experiments using simulated data illustrate the methodology and demonstrate the merits of the suggested method.