Marine animals are increasingly exposed to anthropogenic disturbances that disrupt their behaviour and induce physiological stress. In vertebrates, st…

Natural mortality can be used as a measure of a species’ resilience and is widely used in the management of fish species. Natural mortality can be calculated using life history parameters, although this is often not possible for data-poor species. Acoustic telemetry provides an accurate alternative to estimate natural mortality based on relocations over time. Northern Australia’s river sharks, the Northern River Shark (Glyphis garricki) and Speartooth Shark (G. glyphis), are two rare and threatened species occurring in rivers, estuaries, and inshore marine waters. This study aimed to use acoustic telemetry to estimate natural mortality across a range of size classes and explore the effect of size class, season, and location on mortality rates. An acoustic receiver array was deployed in rivers of Van Diemen Gulf, Northern Territory, Australia. Detections from 185 sharks between 2013 and 2024 were converted into capture histories, which were used to calculate yearly and monthly estimates of mortality. Data demonstrate that river sharks experience high rates of mortality. Younger individuals had significantly higher rates of mortality, with G. glyphis and G. garricki neonates experiencing average yearly mortality rates of 0.898 and 0.731, respectively, compared with 0.120 and 0.233 in subadults/adults. Although mortality was highly variable temporally, over months and years, there were no significant differences between seasons, years or location, and there was no significant difference between species. Results indicate that river sharks in Van Diemen Gulf likely have very limited capacity to recover from population decline and are therefore vulnerable to environmental change and anthropogenic threats. Population monitoring and habitat management is critical to ensure the persistence of river sharks into the future.

Researchers have been studying white sharks on Cape Cod for nearly two decades, and they've been noticing some changing habits over the last couple of years following what seems like an explosion of s...

Sharks play an essential role in maintaining the health of ecosystems, but many species are endangered and have locally disappeared around the world. …

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Rapid DNA/eDNA-based ID tools, which detect specific genetic patterns without requiring sequencing, are essential for biodiversity and wildlife trade monitoring, particularly for species of conservat....

Reproductive behaviors in wild sharks remain largely undocumented, yet they are critical for understanding population dynamics and informing conservation strategies. The Indo-Pacific Leopard shark (St...

The study of the feeding ontogeny of large predators is complex due to their high mobility, which leaves a part of their life cycle poorly understood (spatio-temporal variation). This study describes ...

Scientists conducting a first-of-its-kind drilling operation have extracted samples of fresh water hiding in massive reservoirs deep under the ocean.

The film 'Jaws' has historically given sharks a bad rap, but the 50th anniversary can breathe new life into caring about the ocean.

Abstract. The official data on Russian catch of sharks, rays and skates in the Pacific region over the last 45 years are analyzed. For Russian fishermen th

Context The white shark (Carcharodon carcharias) is a marine predator with a global distribution, ranging from neritic to oceanic waters. In the Southern California Bight (SCB), juvenile white sharks ...

White sharks appear to be using New Hampshire waters as “a bit of a highway to get further up the coast,” says researcher Nathan Furey, a conclusion based on data gathered from a partnership with the ...