Long-Term Data Reveal the Associations of the Egg Quality With Abiotic Factors and Female Traits in the Baltic Herring Under Variable Environmental Conditions

In fish, the lipid resources of female form a link between environment and progeny, contributing to contents egg yolk. Variation environmental conditions is therefore expected affect quality via maternal pathways, reflecting female’s response factors before spawning. We investigated content lipids thyroid hormones in ovary eggs Baltic herring during 1988–2019, when salinity Sea first declined then stabilized lower level, winters varied severe mild. The total spawning females decreased by 40–50% study, ovarian concentration followed this trend resulting decrease eggs. suggested hormonal winter temperature was observable also A change took place approximately around 1998 (SE ± 3 years) suggesting that declining salinity, associated with intrinsic female, i.e., fecundity amount deposited into ovary. However, period stable mainly limited resources. As body size over years, it small can be key phenotypic trait reduce impact on variable conditions.