The marbled crayfish (Procambarus virginalis) is a recently discovered freshwater crayfish species, which reproduces by apomictic parthenogenesis, resulting in a monoclonal, all-female population. The animals were widely distributed through the aquarium trade and have established numerous stable wild populations through anthropogenic releases. They are highly prevalent in Madagascar, where they have become a popular source of nutritional protein. As freshwater crayfish aquaculture in open systems is a thriving, but ecologically damaging global industry, alternatives are urgently needed. Although marbled crayfish are often branded by their invasive mode of reproduction, their overall invasiveness is not higher than for other cultured crayfish species. Furthermore, their resiliency and high adaptability provide a strong rationale for evaluating them for closed, and environmentally safe aquaculture approaches. Here we show that marbled crayfish grow to sizes and weights that are comparable to commercially farmed freshwater crayfish. Tailored feed development and laboratory testing demonstrated highly efficient feed conversion, suggesting a considerable capacity for sustainable production in closed systems. We further show that marbled crayfish meat can be readily introduced into European meals. Finally, chemical analysis of marbled crayfish exoskeletons revealed comparably high amounts of chitin, which is a valuable source for the synthesis of chitosan and bioplastics. Our results thus suggest that production of marbled crayfish in closed systems may represent a sustainable alternative for crayfish aquaculture.
We explored the suitability of marbled crayfish as a source of nutritional protein in European meals. Indeed, we found fried marbled crayfish tails (Figure 1A) to be suitable for crayfish risotto, and for appetizers (Figure 1B). Furthermore, the shell waste that was generated in this process, could be easily collected, and preserved by air-drying (Figure 1C). To determine the chitin content of marbled crayfish shell waste, we used a chemical extraction protocol. Because they represent the major source of commercially extracted chitin and because data or material from P. clarkii were not available, we used similarly processed whiteleg shrimp (L. vannamei) shells for comparisons. This revealed a significantly higher chitin content for marbled crayfish than for L. vannamei (2.60% vs. 0.85%, p < 0.05, and Figure 1D). These findings suggest that marbled crayfish represent a valuable source of chitin. To determine the potential of chitin extracted from marbled crayfish, we also produced biodegradable straws.