Review of size- and age-dependence in batch spawning: implications for stock assessment of fish species exhibiting indeterminate fecundity

The views and opinions expressed or implied in this article are those of the author (or authors) and do not necessarily reflect the position of the National Marine Fisheries Service, NOAA. The relationship between reproductive output and subsequent recruitment of new individuals is fundamental to population dynamics. In stock assessments, this relationship is typically quantified by using a spawner–recruit model. Such models were originally developed with population fecundity as the measure of spawners, but most current applications use spawning biomass, calculated as the total weight of mature females (Rothschild and Fogarty, 1989). A critical assumption with this approach is that spawning biomass accurately represents the reproductive potential of a stock. However, this assumption does not always hold (Trippel, 1999; Marshall et al., 2003, 2006) and, when violated, can inject error into assessment models and subsequent management advice (Rothschild and Fogarty, 1989; Murawski et al., 2001; Scott et al., 2006). Thus, recognition is growing for the need to integrate more reproductive biology into stock assessments by replacing spawning biomass with more accurate measures of reproductive potential (Trippel, 1999; Morgan, 2008; Witthames and Marshall, 2008). Review of sizeand age-dependence in batch spawning: implications for stock assessment of fish species exhibiting indeterminate fecundity