VALORIZATION OF INVASIVE CRAB BIOMASS: THE CASE OF THE CHINESE MITTEN CRAB Eriocheir sinensis AND ITS POTENTIAL AS FEED INGREDIENT IN AQUACULTURE

Introduction

Invasive aquatic species are increasingly recognized not only as ecological threats but also as underutilized biomass resources with potential for sustainable valorization . In this study, we investigated the biochemical composition and biomass characteristics of the highly invasive Chinese Mitten Crab Eriocheir sinensis to assess its suitability within a biorefinery framework. Comprehensive analyses were conducted to determine key constituents, including proteins, carbohydrates, and ash content, alongside the the potential for enzymatic protein hydrolyis relevant for industrial applications.

Building on this characterization, we explored potential valorization pathways aligned with established biorefinery concepts, aiming to integrate this biomass into circular bioeconomy strategies . Particular attention was given to its applicability as a feed ingredient, considering both nutritional value and processing feasibility.

To evaluate this potential, a preliminary feeding trial was conducted using raw, untreated biomass as feed for shrimp Penaeus (Litopenaeus) vannamei. Apparent digestibility coefficients were determined to assess nutrient availability and overall feed performance. The results provide initial insights into the digestibility and suitability of this invasive species as an alternative feed resource in aquaculture.

Overall, this work highlights the dual benefit of mitigating ecological impacts of invasive species while simultaneously unlocking their value as a renewable bioresource. The findings contribute to the development of sustainable management strategies that couple environmental remediation with innovative biomass utilization.

Characterization of Biomass

Figure 1 Degree of hydrolysis for four different enzymes used for the protein extraction of Chinese mitten crab biomass

Figure 1 Degree of hydrolysis for four different enzymes used for the protein extraction of Chinese mitten crab biomass

Biomass of CMC was de-shelled and the pure biomass without carapace/chitin was used for biorefinery approaches. Proximate analysis of CMC showed overall good suitability for feeding purposes in aquaculture, with 53.3 ± 0.17 % crude protein.

The biomass was hydrolysed using four different enzymes, resulting in significantly different degree of hydrolysis (DH, Figure 1), as well as different profiles in aminoacids. All hydrolysates showed good levels of anti-oxidant activity revealed be ABTS and TBAR assays. Here, one-way ANOVA revealed a significant effect of enzyme type on ABTS activity (F(3,8) = 102.43, p < 0.001). Tukey's post-hoc test showed that Alcalase exhibited significantly higher activity than all other enzymes (p < 0.001), while Protamex and Flavourzyme did not differ significantly (p = 0.129). For FRAP, a significant effect was observed (F(3,8) = 4.65, p = 0.036). However, Tukey's test indicated that only Protamex differed significantly from Flavourzyme (p = 0.044), with no other pairwise differences detected.

Apparent Digestibility in Shrimp Penaeus vannamei

The digestibility of biomass from Chinese mitten crab (CMC) were used in a feeding trial with shrimp. We tested raw biomass (with carapace/chitin; CMC+) of E. sinensis and de-shelled biomass (w/o carapace/chitin; CMC-) and a control diet as reference (CTRL). Feces were collected over a 5-week timespan, growth and survival were documented. The AD was calculated for crude protein as well as aminoacids and showed suitable digestibility coefficient. All diets resulted similar survival rates (One-way Anova; F(2,17)= 0.65; p= 0.54) ranging from 92.4 – 97 % and similar hepatosomatic indeces (HSI; F(2,17)= 0.824; p= 0.46) ranging from 3.2 to 3.4, indicating overall good health status during the experimental time. Growth and SGR were highly different between treatments (F(2,17)= 12.4; p < 0.001), with Tukey's pairwise comparisons revealing significant differences between treatments with CMC- resulting in highest and the CTRL displaying lowest growth. This is a first indication for the suitability of CMC as feed ingredient for shrimp. However, this study was designed as digestibility trial, so this results need to confirmed with a growth trial, using isoenergetic and isonitrogenous feeds.

Table 1 Performance data of P. vannamei after the 42 day period of the digestibility trial with diets containing either CMC with chitin (CMC+) or without (CMC-) and a control diet (CTRL). Different superscript letters indicated statistical differences (Tukey's pairwise comparisons, p ≤ 0.05).

Table 1 Performance data of P. vannamei after the 42 day period of the digestibility trial with diets containing either CMC with chitin (CMC+) or without (CMC-) and a control diet (CTRL). Different superscript letters indicated statistical differences (Tukey's pairwise comparisons, p ≤ 0.05).

CTRL

CMC+

CMC-

SGR

1.39

± 0.22^a

1.77

± 0.17^b

2.09

± 0.31^b

Weight gain

9.76

± 1.57^a

12.36

± 1.21^b

14.64

± 2.18^b survival

0.92

± 0.11^a

0.97

± 0.07^a

0.97

± 0.05^a

HSI

3.28

± 0.15^a

3.24

± 0.08^a

3.43

± 0.08^a

Conclusion

Overall, biomass from the invasive Chinese mitten crab shows suitable nutritional profiles. The biomass can be used as raw biomass, but also shows good potential for biorefinery purposes. Protein hydrolysates of CMC biomass revealed aminoacid-profiles suitable for nutrition in aquaculture as well as good functional properties. A first digestion trial of raw biomass with P. vannamei shows its feasibility for the use as aquaculture feeds, but further studies are needed to unfold the whole potential of this underutilized resource.

References

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Fricke, E., Slater, M. J., & Saborowski, R. (2023). Brown shrimp (Crangon crangon) processing remains enhance growth of Pacific Whiteleg shrimp (Litopenaeus vannamei). Aquaculture, 569.

Fuchs, V. I., Saborowski, R., Krost, P., Gingold, R., Hannon, C., & Slater, M. J. (2025). Valorisation of Common Sea Star (Asterias rubens) Biomass as an Alternative Protein Source in Diets for Whiteleg Shrimp, Litopenaeus vannamei. Waste and Biomass Valorization.