Chinese Mitten Crab, Eriocheir sinensis


Scientific Name: Eriocheir sinensis
Common Name(s): Chinese Mitten Crab


THREAT to MAINE

Research Summary
: Max D.


Researching the species wasn't very difficult because there were many resources with a lot of information. I thought it was surprising how much information there was available. Some of the most important things that I discovered were that the female crab can carry 250,000 to 1 million eggs.  Another thing is that the crab came all the way from south China and is now in the San Francisco Bay.


Identifying Characteristics
Claws
  • Hairy claws with white tips.
  • Claws are about the same size.
Body/Legs
  • Round carapace.
  • Carapace width is 3 inches.
  • Carapace is a little longer than wider.
  • Legs are more than twice as long as the carapace width.
  • Its a light brown to an olive green color.
Reproduction
  • The females can carry 250,000 to 1 million eggs.
  • The adults reproduce in salt water and the small offspring migrate to fresh waters.

 


 
 

 

Taxonomy of Species
   Scientific Classification
 What That Classification Means
 Kingdom  Animalia  Eukaryotic, many celled move members eat plant or other animals.
 Phylum  Arthropoda  A group or phylum of animals that have segmented bodies, exoskeletons,
 and jointed legs.
 Class  Malacostraca  Largest subclass of crustacea which have an exoskeleton, which they      
 moult to grow. Include crabs, lobsters, shrimp, sow bugs, beach flies.
 Order  Decapoda  Has ten feet. Includes lobsters, crayfish, crabs, shrimps, prawns, squids 
 and cuttlefishes.
 Family  Varunidae  Varunidae is a family of thoracotrematan crabs.
 Genus  Eriocheir  Genus of crab.
 Species  Eriocheir   Chinese Mitten Crab

Similar species include: Eriocheir Japonicus, (Japanese mitten crab) Eriocheir leptognathus, (Rathbun) and Eriocheir Rectus (Stimpson).


Location and Movement
Origin/ Native Range
 Came from the temperate waters between East Russia (Viadivostok) to south China.
Introduction
  • In 2005 it was caught in crab pots in the Chesapeake Bay.
  • It was found in the Delaware Bay in May, 2007
Spread of Species  Is introduced to new places by its larvae getting in the ballast waters of ships or being brought to
 new places to sell.    
Where is it now invasive?
  • The crab is invasive to the Chesapeake, Delaware, and San Francisco Bays and in the early 1900s it became invasive to Northern Europe.
  • Has spread now to Portugal and southern France.

Maine
Is this species in Maine?
 The species is not in Maine.
Where has it been identified?
 The closest location to Maine is the Delaware Bay, found in May, 2007.
How was this species introduced?  N/A


Habitat
Natural Environment
  • Slow moving, brackish waters.
  • Likes to hide in aquatic weeds or gravels and sands.
  • Can survive in polluted water habitats and has adapted to be to walk on land.   
Climate and Temperature Range
 Preferred temperature range is between 10 C to 25 C (50 F to 77 F).


Nutrition
Ecological Interactions  It is a consumer and an omnivore.
Obtaining
 It eats small fish, prawns, tender macrophytes, plants, zooplankton, and phytoplankton.
Consumed By
 Pike, eel, brown trout, white sturgeon, striped bass, large mouth bass, sunfish, bullfrogs, loons,
 egrets, wading birds, river otters, raccoons.    


Impact
Ecological
  • Consumes nutrients needed by native species thus reducing biodiversity and reducing competition.
  • Consumes fish eggs which places some species at risk such as California's endangered salmonoids.
  • Impacts rare endangered crayfish species because they share the same diet.
Human
  • They break traps and nets and steal fish bait.
  • Burrowing of the Chinese mitten crab can have a result in damaging river embankments and erosion.
  • The crab is the second intermediate host for the human lung fluke parasite that is in Asia.
Economic
  • They damage rice plants in China.
  • A loss in commercial fisheries due to the crabs feeding on fish that are caught in traps or nets.
Benefits
  • Is eaten in China.
  • Used as bait for eel fishing.


Control
Biological  Some things that eat it are pike, eel, brown trout, white sturgeon, striped bass, largemouth bass,
 sunfish, bullfrogs, loons, egrets, wading birds, river otters, raccoons.   
Mechanical
  • In Germany traps were set up to capture juvenile crabs as they migrated upstream.
  • Installation of "traveling screens" and trash racks will reduce the population during the migration events its best done in a place where the river is entirely contained by a regulatory structure like a dam.
Cultural  Development of programs that educate the public on the health and invasive risks of the Chinese 
 mitten crab.
Chemical  Chemical control has never been an option due to the species dispersal.


Interesting Facts
  • In Germany the crab had dug burrows that where 2 feet deep and closely spaced.
  • The crab was introduced into Germany waters in the 1900's. 
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