Where did the Chinese mitten crab come from & how did it get here?
Originally from the Yellow Sea in South East Asia
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The Chinese mitten crab (Eriocheir sinensis) is indigenous to South East Asia from the coastal rivers and estuaries of the Yellow Sea in China and Korea [1, 2]
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Brachyuran species of the order Decapoda
Figure. 2. Map of the Yellow Sea. CC BY-SA 3.0
Biology, Life Cycle, & Reproduction
Furry "Mittens"
Figure 1. Zoo Köln Eriocheir sinensis 31122014 1 bis.jpg_ by user_Vassil is licensed under CC BY-SA 4.0
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Adults have a dense patch of setae (fur), on their chelae (claws).
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The purpose of the fur is still unknown [1].
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Males - Claws have a complete covering of fur.
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Females - Claws have a strip without fur on underside [2].
Behavior, Human Impacts, & Global Expansion
Impact on "Native" Ecosystems
Figure 7. Chinese mitten crab Crabe chinois (Breemwaard, Waal) zoom.jpg_ by Peter Jesse is licensed under CC BY-SA 4.0
Opportunistic feeder:
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Preys on diversity of plants and animals, including native species.
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Eats vegetation, detritus, mollusks, crustaceans (amphipods, water fleas, and shrimp), fish, and aquatic insects.
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Eats salmon, trout, and sturgeon eggs (in US West coast) [1, 2, 4]
Predator & competitor:
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Outcompetes freshwater crayfish (e.g. endangered European crayfish) [1].
Aquaculture
Chinese Mitten Crabs (AKA Shanghai Hairy Crabs)
A Delicacy in the "Far East"
Figure 12. File_SZ 深圳 Shenzhen 南山區 Nanshan District WalMart food 大閘蟹 Chinese mitten crabs live Sept 2018 IX2 04.jpg_ by TIUCHOITHIA Luk is licensed under CC BY-SA 4.0
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Recent E. sinensis aquaculture efforts in China [2, 3].
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Advances in mass seed production
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Potential impacts on local ecosystems should be considered [3].
Figure 13. File_Iz - Eriocheir sinensis - 1.jpg_ by Emőke Dénes is licensed under CC BY-SA 4.0
Some Chinese mitten crabs may have been deliberately introduced into San Francisco.
to start a fishery [1, 2].
Carriers of Disease?
Carrier of
"Oriental" Lung Fluke Parasite
in Asian Countries
Figure 14. Paragonimiasis is caused by the lung fluke Paragonimus westermani which is most prominent in Asia and South America. Infection in humans is contracted by the ingestion of a crab or crayfish harboring the metacercariaeImage by Yale Rosen from USA / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.0)
In its native range, the Chinese mitten crab carries a lung fluke trematode parasite Paragonimus westermani that infects humans. This causes a condition known as paragonomiasis, a tuberculosis-like condition of the upper lung [2].
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The intermediate host for P. westermani is a snail of the genus Semisulcospira, which is not present in the USA and Northern Europe.
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Only in China, Japan, Taipei, Korea and Vietnam. Not found in Europe or North America.
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Risk of parasitism in invasive mitten crabs therefore remains extremely small [2].
Vector of Crayfish Plague Pathogen in Germany
The Chinese mitten crab was recently identified as a vector (carrier) of the crayfish plague pathogen Aphanomyces astaci [6], a disease fatal to native European crayfish species [3].
Figure 15. Crayfish plague (Aphanomyces astaci), sporulation. Image by Bram Koese / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)