The daily fecundity reduction method: a new procedure for estimating adult fish biomass

Abstract

A new method was developed for estimating adult fish biomass from the daily decline in reproductive potential of the population and the numbers of planktonic eggs. Decline in reproductive potential was estimated from the product of the daily decline in the standing stock of advanced oocytes in ovaries and the daily decline in the numbers of females with reproductively active ovaries. Daily production of planktonic eggs was estimated from the number of eggs in quantitative oblique plankton tows. The method is restricted to fishes in which the potential annual fecundity becomes fixed prior to the onset of the spawning season, that is, fishes with determinate annual fecundity. The method was applied to data for Microstomus pacificus, commonly known as Dover sole, a pleuronectid flatfish of the upper continental shelf (200–1500 m) of the west coast of North America.