Dr. Julia Constance is back on Beyond Jaws, and this time she's joining hosts Andrew Lewin and Dr. David Ebert as Dr. Constance. Julia returns fresh off completing her PhD on the natural mortality and movement ecology of two of the world's least understood sharks: the speartooth shark and the northern river shark, both found almost nowhere outside northern Australia and southern Papua New Guinea. Using a long-running acoustic telemetry dataset built by her supervisor since 2013, Julia tracked around 200 tagged sharks across Northern Territory river systems, some for up to a decade, to understand how these animals move, where they go, and what puts them at risk.

The conversation digs into just how little is still known about these sharks once they leave the rivers as adults. Julia explains how individuals vanish from the tracking data for years at a time before reappearing at a river mouth, with almost no confirmed sightings of adults in the open marine environment. She and the hosts also compare the relatively stable status of Australia's river sharks to their close relative, the Ganges shark, a species so rare and poorly documented that even basic facts about its biology are borrowed from research on its Australian cousins.

Along the way, Julia and Andrew share what it's actually like to do this fieldwork: murky, chocolate colored water, gear retrieval by feel instead of by sight, and working in rivers that hold the largest population of saltwater crocodiles on the planet. The episode also touches on a real and growing concern: proposed water resource development on the Adelaide River, home to the largest known population of speartooth sharks anywhere in the world, and what that could mean for a species already living in an extremely narrow habitat.

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