Births: Fertile females mate one time only, in the summer months, each producing millions of eggs (1 - 8 million) (1 - 2 million). The eggs need salinity to hatch. The larvae wash into the ocean, then swim back upstream into the Bay, settling in the Bay shallows for the winter. Males mate multiple times.
Survival rate: One scientist estimated that one in a million eggs survive to reach adult crab status. How do we incorporate qualitative factors such as climate, habitat, and predators into the survival rate? One scientist estimated that 80% of yearly variation is caused by weather.
Life Span: 2 - 3 years (females - 2, males - 3)
Predators of crabs: Larger crabs, blue heron, raccoon, rockfish, white perch, cownose ray, American eel
Crab food: small fish, young oysters and clams, smaller crabs
Diseases/Parasites: protozoan amoeba, chemical pollution, worms
Crabbers catch of adult crabs: (50-92% of harvestable crabs)
(in millions of pounds) (in millions of crabs)
Commercial Commercial Recreational
1988 80 240
1989 85 255
1990 95 285
1991 92 274.5 70
1992 54 164.1 70
1993 113 339
Historical data on crab population:
Winter of
1988-89 1.75 billion (first year of survey, may be erroneously high)
1990-91 893 million
1991-92 440 million
1992-93 665 million
1993-94 665 million
1994-95 565 million
Legislation proposed to reduce crabbing:
Season end: November 15 instead of December 31
Commercial:
Hours: 6 am - 2 pm instead of 4:30 am - 5:00 pm
Days: 6 days instead of 7 days (drop a slow day)
Recreational:
Hours: 7 am - 5 pm instead of 5 am - 5 pm
Days: 3 days instead of 7 days (keep Friday - Sunday)