The speartooth shark (Glyphis glyphis ) is found in several river systems in northern Australia and is listed as critically endangered under Australian EPBC legislation. Previous work has documented that bycatch in crab fisheries has been a key threat to the species in some of its natal river systems. We describe a comprehensive update of understanding of speartooth shark populations in a key population (the Wenlock River) via close-kin mark recapture estimates of adult abundance and physical mark recapture to estimate abundance of juvenile sharks. Our analysis found a ~34% decline in adult abundance over 2008-2025 and a juvenile population of around ~300-500 individuals annually. This allowed us to estimate litter size in the species and update previous estimates of adult sex ratio. From 3205 crab pot set observations of commercial fishing effort with and without excluder devices, we estimate that catch rates of speartooth sharks was ~40 times lower in pots fitted with excluders. From long-term acoustic telemetry studies, we estimated spatial usage of the Wenlock system. Based on this updated knowledge of the population abundance and distribution we constructed population models compared the effect of gear modification and hypothetical spatial closures on population recovery rates.