Meat Nutritional Value and Exoskeleton Valorisation of Callinectes sapidus from Three Sites of Biological and Ecological Interest in Morocco: Scientific Insights Toward a Management Strategy in the Mediterranean Sea

Biological invasions threaten biodiversity worldwide. The American blue crab Callinectes sapidus Rathbun, 1896, among the Mediterranean’s most damaging invaders, takes up the challenge to transform this threat into gain. To turn its impact into economic value and guide control efforts, we analysed separately the meat composition and exoskeleton biopolymers of adult crabs from three Moroccan protected Sites of Biological and Ecological Interest: Marchica Lagoon (S1), Moulouya Estuary (S2), and Al Hoceima National Park (S3). Marchica specimens exhibited the highest protein content (21.87 ± 1.15 g 100 g−1, p < 0.001) and an elevated lipid fraction, yielding nutrient-dense meat suitable for premium markets. Moulouya crabs were noted for their taste potential, with a higher concentration of fat (1.73 ± 0.09%) and carbohydrates (0.91 ± 0.1%). Al Hoceima individuals displayed markedly mineralised exoskeletons producing lean and low-fat meat, valued in dietary applications. Exoskeleton organic-to-mineral (OM/MM) ratios and proximate composition revealed three adaptive profiles, opportunistic (S1), acclimatory (S2), and conservative (S3), presumably correlated to local salinity, productivity, and substrate conditions, underscoring the species’ phenotypic plasticity. X-ray diffraction confirmed the α-chitin polymorph, while FTIR analysis indicated degrees of deacetylation consistent with high-purity chitosan. These findings support the development of a site-specific circular economy framework and may contribute to the ecological resilience of Morocco’s protected coastal areas.