Maternal and interannual comparison of the ovulatory periodicity, egg production and egg quality of the batch‐spawning yellowtail flounder

Abstract

Estimates of the ovulatory periodicity of yellowtail flounder indicate that a 1‐day interval, which predominated over all other intervals, may characterize regular ovulation patterns. Females produced a mean number of 14–22 batches in 1994 and 1995, respectively. Batch fecundities usually remained within a range of 10 000–60 000 eggs. Mean egg production increased from 549 756 eggs per female in 1994 to 1 186 881 eggs in 1995. Mean fertilization rates rose interannually from 38 to 57%, while hatching rates, tested in 1994, had a mean of 63%. Maternal variation in egg production and egg quality was large and independent of size differences among females. Some females had disrupted ovulation patterns which affected the realization of potential fecundity contained within the prespawning ovary. High interbatch variation in egg quality was not related to progressive decreases in egg diameter and dry weight over time. Batches with high survival rates appeared at random within a female's duration of ovulation.