The Red Sea's largest coastal lagoon is a reproductive site for endangered whiprays and guitarfish

Safeguarding reproductive habitats can be crucial to sustaining batoid populations, yet such areas remain poorly documented, particularly in the Red Sea. This study used ultrasonography to assess seasonal patterns of pregnancy in 2 threatened batoids, the halavi guitarfish Glaucostegus halavi (Critically Endangered) and the reticulate whipray Himantura uarnak (Endangered), from the Red Sea's largest coastal lagoon (Al Wajh Lagoon, Saudi Arabia). In total, 15 G. halavi and 6 H. uarnak were confirmed pregnant in the lagoon, providing the first evidence of a gestational site for batoids in the Red Sea. These records refine minimum female size-at-maturity estimates for both species (82 cm disc width for H. uarna k; 91 cm total length for G. halav i ), which until now have remained unresolved. Male reproductive assessments revealed that maturity is reached at least at 76.3 cm total length in G. halavi and 76.7 cm disc width in H. uarnak . Additional observations of neonates, smaller than previously reported size-at-birth for each species, and aborted foetuses from a fishery-landed G. halavi provide suggestive evidence that parturition may also occur within the lagoon. These findings advance our understanding of reproductive biology in threatened batoids, highlight the Al Wajh Lagoon as a multi-species reproductive site of regional conservation importance, and underscore the need for expanded sampling.