Increased temperatures favour reproductive investment in smaller over larger female common sole (Solea solea) in the Northeast Atlantic

Abstract

Reproductive investment is a major life history trait affecting individual fitness. Understanding reproductive investment is important to assess population dynamics under current and future environmental changes. A major environmental change that affects the reproductive investment of fish populations is local warming under on-going climate change. In this study, we investigated the effects of increased temperature on the reproductive investment of female fish across different body sizes (measured as total length). To this end, we applied a mixed-effects modelling framework to a large dataset of 4637 observations of ovary weight from developing-stage female individuals collected from 2004 to 2022 from four populations of common sole (Solea solea): the North Sea, Irish Sea, Bristol Channel-Celtic Sea North, and Eastern English Channel populations. We found that increased temperature had different effects on fish reproductive investment across body sizes, i.e. enhanced reproductive investment in smaller individuals, but reduced investment in larger individuals in the North Sea and Irish Sea sole populations. No significant size-specific temperature effect was detected in the Bristol Channel-Celtic Sea North and Eastern English Channel populations. In addition, we found that the reproductive investment of sole exhibits hyper-allometric scaling (positive allometry) with body size. Our study sheds light on how temperature changes influence fish reproductive investment, with implications for population dynamics.