UTTAR PRADESH JOURNAL OF ZOOLOGY

Climate change is altering the environmental conditions experienced by aquatic organisms through rising temperatures, marine heatwaves, hypoxia, salinity fluctuations, ocean acidification and more frequent extreme events. Although the effects of climate change on growth, survival and disease have received considerable attention, reproductive impairment may occur before substantial mortality and can directly threaten aquaculture seed production. Reproduction depends on the coordinated interaction of environmental cues, neuroendocrine pathways, gonadal function, gametogenesis and energy allocation, making it particularly sensitive to environmental instability. In fish, climate-related changes can affect the brain–pituitary–gonad axis, steroidogenesis, sex differentiation, gametogenesis, gamete quality and spawning. Temperature is especially important because it influences endocrine regulation throughout reproductive development, while hypoxia, salinity changes and ocean acidification can further modify endocrine, metabolic and cellular processes. In shellfish, environmental stress can affect gonadal development, gametogenesis, spawning, fertilisation and larval performance through mechanisms that differ from those operating in vertebrate fishes. Multiple climate-related stressors may also act simultaneously, producing additive, synergistic or antagonistic effects. Parental exposure can further influence offspring through maternal provisioning, paternal effects and epigenetic mechanisms. These processes have direct implications for broodstock conditioning, hatchery seed production and the sustainability of aquaculture. This review examines the links between climate-related environmental change, reproductive endocrine regulation and reproductive performance in cultured fish and shellfish, with emphasis on gamete quality, spawning, early development, multiple-stressor interactions and reproductive resilience. Environmental management, broodstock selection, nutrition, acclimation, selective breeding, biomarker-based monitoring and climate-resilient hatchery technologies are considered potential approaches for sustaining reproductive performance under future environmental conditions.