The maternal effects and the oocyte dynamic are analysed in the Southern Stock of European hake (Merluccius merluccius) to compare spawning performance between the two observed spawning seasons and better understand reproductive potential dynamics in this stock. The complex Oocyte Packing Density method (OPD) has been used to analyse the oocyte dynamic in a temporal scale and by ovary phase; while five different maternal attributes have been used to investigate the maternal effects on six egg traits as proxy to egg productivity and offspring quality. Our results show that oocyte recruitment for the current breeding season initiates well before secondary growth stage, during the 80-90 µm previtellogenic oocyte stage. This allows estimating an index of potential fecundity and even potentially to estimate the number of batches to be produced. Maternal effects showed differences between spawning seasons in terms of productivity and egg quality. Although maternal effects were relative weak, it indicates that the current truncated demography may have produced a reduction in stock reproductive potential and hence affecting recruitment and fisheries sustainability.
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