Cancer magister, Dungeness crab

Interactions

The Dungeness crab has several interactions with many marine species, but the most important is their interaction with humans.

 Marine Interactions                   

 Nadelspora canceri, a microsporidian

 Nadelspora canceri is a parasite to the Cancer magister, and also the most pathogenic parasite of crustacean diseases.  In this interaction the Cancer magister acts as the host to this parasite.

The parasite infects the muscle tissues which causes a white discoloration in the muscle and ultimately leads to muscle destruction.

 The prevalence of infected crabs can range from 1.4% to 48% depending on the collection site.  The highest concentration of infected crabs was found in estuaries, and it was more prevalently found in younger 1 to 2 year old crabs.

 

Chlamydia-like bacteria

This Chlamydia-like organism is a Gram-negative bacterium that infects the gills of the crab. 

It was responsible for extreme mortality in Willapa Bay, WA in the 1980s.  Dr. Sparks discovered that the disease occurred only in local crab population in winter and spring.  It is believed to be only prevalent during extreme cold weather which suppresses the crabs immune system.

 

Common Predators

Nemertean worm, Carcinonemertes errans: This worm commonly eat the eggs of the Dungeness crab

 halibut, dogfish, sculpins, octopus, and sea otters

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Human Interactions  

Crab fishing is a multi million dollar industry and many west coast communities economies are based on the years harvest.  This is why the Cancer magister is such an important organism because many people rely on the population of this organism.  In Oregon alone each fishing boat can be carrying a value ranging from $5 million to $44 million alone, showing just how prized these crabs are.

 Each year the Dungeness crab population is fully exploited, 80-90% of all available legal sized males are caught.  Since females are illegal to catch, the population still can be sustained by the ability to mate with younger males and sustain the population.

 

Last, check out the Interesting facts of the Dungeness crab.