Implications of Maternal Toxicant Effects on Size‐Dependent Fisheries' Management: A Meta‐Analysis

ABSTRACT Bioaccumulation of environmental toxicants in aquatic ecosystems presents a significant ecological challenge including potential implications for fish reproduction and population dynamics. Through this meta‐analysis, we investigated how elevated mercury (Hg) and polychlorinated biphenyls (PCBs)—two prevalent and problematic contaminants—in large, and presumably old fish, affect toxicant concentrations in their eggs and subsequent offspring success. We synthesized published data to analyse: (1) the association between maternal size and egg toxicant loads, (2) the relationship between maternal muscle toxicant concentrations and egg toxicant loads and (3) the impact of egg toxicant loads on offspring hatching success, mortality and growth. Our results revealed that maternal size was strongly, positively associated with egg toxicant concentrations, with Hg showing an effect size nearly double that of PCBs. Similarly, toxicant concentrations in maternal muscle tissues were strongly, positively associated with egg concentrations for both contaminants. Additionally, elevated egg toxicant loads were associated with decreased hatching success and increased offspring mortality, whereas impacts on growth rates varied by toxicant, highlighting negative impacts on early life stages. These findings have important implications for fisheries management, particularly regarding the protection of ‘big old fat fecund female fish’ (BOFFFFs). Although BOFFFFs typically produce numerous eggs, our study shows these benefits may be offset by increased toxicant transfer to offspring in contaminated systems. Management strategies should consider the reproductive benefits of BOFFFFs and the potential disadvantages of maternal toxicant transfer when establishing conservation priorities, especially in historically or currently contaminated systems or populations more susceptible to bioaccumulation.