Annual Fecundity of European Anchovy: A Case Study in the North Aegean Sea (Eastern Mediterranean)

Egg production estimates are key indicators of stock reproductive potential. In indeterminate spawners, annual fecundity cannot be estimated prior to the spawning season and, instead, requires quantification of batch fecundity and spawning frequency along the entire spawning period. In the present study, we provide the first estimate of annual fecundity of European anchovy (Engraulis encrasicolus) in the Mediterranean Sea (Northeast Aegean Sea). Monthly samples collected throughout 2019 were used to delimit the duration of the spawning season and provide monthly estimates of batch fecundity and spawning frequency. Furthermore, monthly variations in stage-specific relative oocyte numbers were examined using stereology and oocyte packing density theory. Spawning activity occurred mainly from April to September and spawning frequency of spawning capable and actively spawning females ranged from 0.25 to 0.35. Due to the limited number of females with hydrated oocytes, batch fecundity was assumed to exhibit seasonal stability. The relative number of vitellogenic oocytes did not change significantly along the spawning period which supported this assumption. The calculated total number of spawnings per year was 55 and relative annual fecundity was ~20,000 eggs g−1. These findings provide essential input for daily egg production method applications and can improve parameterization of individual-based bioenergetic models.