West Coast Venus Clams
Chione californiensis, Chione undatella
Chione californiensis and Chione undatella are two species of venus clams found on the west coast of North America. There is no established fishery for venus clams in California, but ongoing research identifies aquaculture potential for the species.
Photo by Theresa Talley
- Mean (±1SD) length 2.94 ± 0.22 cm; maximum length of around 6.35 cm. 
- Color range varies, including white, ivory, gray, pale pink. 
- Radiating bands and very closely spaced radial and concentric ridges (C. californiensis and C. undatella, though C. undatella ridges are more closely spaced). 
- From Point Conception, Santa Barbara County, California (lat. 34°25'N) to Panama. Few findings of Chione all the way down in Peru from limited records. 
- Most relatively abundant clam in the intertidal zone in some sites along the Pacific coast of Baja California Sur. 
- Actively spawns in warmer months (June to September) with a peak in August when temperatures are near 29°C. 
- Gametogenesis is directly related to variations in temperature; the frequency of spawning individuals increases with rising temperature and vice versa. 
- External fertilization; Gametogenic progression in male and female clams is categorized by five stages: inactive, gametogenesis, ripe, spawning and spent. [3,7]
- Embryos develop into free-swimming trocophore larvae, succeeded by the bivalve veliger resembling a miniature clam. 
- The size at first maturity is 57 mm LC for relative species (Chione undatella). 
- Life span of 1-2 years (C. californiensis and C. undatella).
- Predominantly found in the intertidal zone 
- Higher abundance in areas with fine/very fine sand, or sand-silts with lower abundance in sediment containing clay. 
- On flats of sloughs, coves and bays, primarily in the intertidal zone (as deep as 50 m).
- C. californiensis: Ideal temperatures for spawning: ~ 22-30 ℃; Spawning is interrupted when temperatures fall below 24°C. 
- C. undatella: Species does not grow below 17 ℃ (62.6 °F) with ideal temperature: ~17-24℃ (62.6 - 75.2°F). 
- Gastric content observed to be only phytoplankton. 
- Holocanthus passer angelfish have been known to prey on these clams in Mexico; limited information on other predators. 
- Available year-round
Regulatory and Managing authority
- The California Department of Fish and Wildlife (CDFW) requires clam diggers to have a valid sports fishing license. 
- Rakes and shovels are commonly used to dig through the sand. 
Status of the fishery
- There is no established fishery for venus clams in California, but current research identifies aquaculture potential for the species.
Potential ecosystem impacts
- No potential ecosystem impacts have been identified.
- The entire soft-bodied clam is edible. 
Description of meat
- Firm and sweet. 
- Most often steamed. 
- Can be included in pastas, soups, or rice. 
- No current nutritional information is available.
- Venus clams have the potential to naturally accumulate domoic acid toxins, which can be a health hazard for human consumption. 
- The Office of Environmental Health Hazard Assessment (OEHHA) also issues consumption advisories based on the amount of mercury or other chemical toxins found in finfish, shellfish and crustaceans. 
- Available year-round.