In the Mediterranean, more than one shark or ray species out of two is threatened with extinction, making this basin one of the most critical global hotspots for elasmobranchs. Over one third of these species are classified as threatened, while many others remain poorly studied or not yet assessed.

Yet more than one third of sharks and rays play key ecological roles in maintaining the balance of marine ecosystems. Sharks directly regulate populations of herbivores and smaller predators and help limit disease spread by preferentially preying on weakened or affected individuals. Some ray species, by disturbing sediments while foraging, structure and oxygenate the seabed, thereby enhancing benthic biodiversity. Their decline is driven by multiple pressures: fishing, coastal habitat degradation, pollution and climate change.

A major obstacle to their protection lies in the lack of knowledge about their movements, breeding, feeding and nursery areas. Elusive, mobile and low in abundance, sharks and rays often escape conventional monitoring methods. In the absence of precise data, management and conservation measures remain partial and sometimes poorly adapted.

The Gulf of Lion and the Cerbère‑Banyuls Marine Reserve nonetheless provide a unique opportunity to address these gaps, thanks to an existing network of acoustic receivers and observations suggesting the seasonal presence of sensitive species.