The Overlooked Threat of Global Warming on Elasmobranch Fertility

Abstract

Climate change is increasingly recognised as a critical threat to global biodiversity, yet its impacts on reproductive processes remain poorly understood in many marine taxa. Elasmobranchs (sharks, skates and rays) represent a particularly vulnerable group due to their peculiar life histories, low fecundity, and diverse reproductive modes. In this review, we synthesise current knowledge on how rising ocean temperatures may affect elasmobranch fertility across key stages of the reproductive cycle, including gametogenesis, mate searching, sperm storage, fertilisation, embryonic development, and offspring production. Evidence from 88 species suggests that thermal stress could impair sperm and oocyte quality, disrupt reproductive timing, alter embryonic growth and survival, and potentially exacerbate sexual conflict. While some reproductive strategies such as embryonic diapause, sperm storage, or behavioural thermoregulation may provide short-term buffering capacity, their effectiveness under rapid and sustained warming remains uncertain. We further highlight the macroevolutionary significance of elasmobranch reproductive diversity, as well as the conservation implications of fertility constraints under global change. Addressing these knowledge gaps is essential to refining demographic models, improving extinction risk assessments, and guiding the design of climate-resilient management strategies, including fisheries regulations and marine protected areas. By explicitly linking reproductive biology with conservation policy, we argue that understanding thermal fertility limits is key to predicting elasmobranch population trajectories in a warming ocean.