St. Lawrence species

Northern propellerclam

Cyrtodaria siliqua

Type of resource

  • Seafood
  • Seafood - molluscs

Status of the resource

  • Not determined

In season

SIZE : Up to 11 cm in length and 5 cm in width..

LIFRE EXPECTANCY : Over 100 years.

LIFE CYCLE : Sexual maturity around 5 years, at a size of approximately 3 cm.

The northern propellerclam is a sexed species, having both males and females. Its reproduction happens ”on the fly”, meaning that the females release a large number of eggs, which are then fertilized in the water column by the sperm released by the males, thus requiring a certain density of conspecifics for reproduction to be effective.

Growth is relatively rapid up to the age of 20, after which it slows down.

Credit : Claude Nozères, photo taken at Rimouski-Neigette, in 2008.

The northern propellerclam is a stocky shellfish. Its soft body extends well beyond its shell.

Its shell, whitish or bluish in color, is long and robust. Its valves are marked by an oblique fold, giving it a twisted appearance. A soft, shiny sheath, ranging in color from light brown to black, covers it completely, including the exposed meat.

Buried in sandy bottoms, usually between 50 m and 150 m deep, but can reach depths of 600 m.

The northern propellerclam favors cold waters, between -1 ° C and 6 ° C. It buries itself completely in the sand, just a few centimeters deep.

The northern propellerclam filters water to feed.




Most predators will eat it whole, shell included.




Yellowtail flounders



MACHINES : Hydraulic edges.

REGULATION : Fishermen of offshore clams, i.e. Stimpson’s surf clams and northern quahogs, are permitted to harvest northern propellerclams as an unrestricted incidental catch. There is no directed fishing for the northern propellerclam.

They are blanched and frozen on board the fishing vessels.

LET’S COOK Soft meat with a taste similar to that of cucumber when raw; firm when cooked. Its body texture is rather tender, while the siphon texture is tougher. The northern propellerclam is perfect for sushi and sashimi.


  • Wash the propellerclams in a mixture of the juice of one lemon and two cups of water (500 ml) for 10 to 20 seconds. This brings out the propellerclam’s natural crunch and softens its strong flavor.
  • The siphon can be cut into strips for marinating or added to a seafood dish.