New kid in town: the Mediterranean outbreak of Callinectes sapidus, its road to valorization and the Italian paradox

The invasion of the Atlantic blue crab, Callinectes sapidus , in the Mediterranean has evolved from a 20th-century lag phase into an explosive demographic surge. Driven by tropicalization and marine heatwaves, this expansion has triggered a systemic ecological and socio-economic crisis, particularly in the Northern Adriatic. We review current knowledge on the invasion history of C. sapidus in the Mediterranean, the environmental drivers underpinning the demographic expansion that started in 2019-2020, and its impacts on biodiversity, aquaculture, and ecosystem services. This review identifies a critical "Italian paradox": while biomass reached unprecedented levels in 2025, exceeding 2,200 tonnes in the Po Delta alone, the management response remains reactive, focusing on costly disposal rather than high-value exploitation. A transition toward a Blue Biorefinery model is suggested to be the key to resolve this paradox. Beyond its culinary value, C. sapidus is a reservoir of high-value compounds, including medical-grade chitosan, antihypertensive peptides, and astaxanthin, with very high market value. By implementing green extraction technologies, a biological threat can be transformed into a self-sustaining circular economy. However, industrial scaling must integrate rigorous monitoring of heavy metal bioaccumulation and emerging pathogens to ensure safety.