Identifying bivalve shellfish

Learn how to identify the main species of bivalve shellfish harvested in Canada.

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Clams

Species of harvested clams include the following.

Arctic wedge clam (Mesodesma arctatum)

  • Maximum length: 4 cm
  • Colour: greyish-white
  • Shape: wedge
  • Location: Atlantic coast
  • Habitat: continental shelf waters to depths of 90 m
  • Note: this clam is unique because it doesn’t shrink once cooked
Atlantic Surf Clam

Atlantic surf clam (Spisula solidissima)

  • Maximum length: 17.5 cm
  • Colour: yellowish-white
  • Shape: V-shaped
  • Location: Atlantic coast
  • Habitat: shallow holes in sand bars or ocean floor to water depth of 75 m
  • Note: also known as a bar clam
Butter clam

Butter clam (Saxidomus gigantea)

  • Maximum length: 13 cm
  • Colour: yellow or greyish-white
  • Shape: square or oval
  • Location: Pacific coast
  • Habitat: holes under tidal beach or ocean floor to water depth of 15 m
  • Note: stays on a single beach for life
Geoduck clams

Geoduck clam (Panopea generosa)

  • Maximum length: the shell is 20 cm
  • Colour: the shell is white and the neck is reddish-brown
  • Shape: the shell is rectangular
  • Location: Pacific coast
  • Habitat: holes under tidal beach or ocean floor to water depth of 100 m
  • Note: long neck
Native littleneck Clam

Littleneck clam (Protothaca stamineais)

  • Maximum length: 7 cm
  • Colour: white or grey with brown areas
  • Shape: round
  • Location: Pacific coast
  • Habitat: holes under tidal beach or ocean floor to water depth of 12 m
  • Note: rings on shell show the clam’s age
Manila Clam

Manila clam (Venerupis philippinarum)

  • Maximum length: 7.5 cm
  • Colour: yellow, brown or grey
  • Shape: oval
  • Location: Pacific coast
  • Habitat: shallow holes in tidal beach sand, gravel or mud
  • Note: native to Japan, accidentally introduced to Canadian waters during the 1920s or 1930s
Bay quahog

Quahaug (Arctica islandica)

  • Maximum length: 13 cm
  • Colour: yellowish-brown
  • Shape: oval
  • Location: Atlantic coast
  • Habitat: holes under tidal beach or ocean floor to water depth of 250 m
  • Note: among the slowest growing clams harvested commercially
Razor shells

Razor clam (Siliqua patula)

  • Maximum length: 25 cm
  • Colour: brown or olive green with a small purple area
  • Shape: oval
  • Location: Atlantic and Pacific coasts
  • Habitat: holes under tidal beach or ocean floor to water depth of 20 m
  • Note: shell has a sharp edge
Softshell Clam

Softshell clam (Mya arenaria)

  • Maximum length: 9 cm
  • Colour: milky white
  • Shape: oval
  • Location: Atlantic and Pacific coasts
  • Habitat: holes under tidal beaches and ocean floor
  • Note: top and bottom shells are different
Stimpson's Surfclam

Stimpson surf clam (Mactromeris polynyma)

  • Maximum length: 15 cm
  • Colour: yellow or brown
  • Shape: an oval or sometimes triangular shell
  • Location: Atlantic, Pacific and Arctic coasts
  • Habitat: holes under tidal beach or ocean floor to water depth of 100 m
  • Note: difficult to distinguish from the Atlantic surf clam
Varnish clams

Varnish clam (Nuttallia obscurata)

  • Maximum length: can grow to 38 mm in about 4 years, but size and age at maturity aren't known
  • Colour: shiny brown
  • Shape: round
  • Location: Pacific coast
  • Habitat: intertidal zone of sand/gravel beaches, and often found in streams, freshwater runoff or groundwater seepage
  • Note: also known as a savoury clam

Mussels

The following single species of mussel is harvested.

Blue Mussel

Blue mussel (Mytilus edulis)

  • Maximum length: 10 cm
  • Colour: bluish-black
  • Shape: sides may be straight or curved
  • Location: Atlantic and Pacific coasts
  • Habitat: inshore waters
  • Note: this species is farmed in the Maritimes

Oysters

Species of harvested oysters include the following.

American Oyster

American oyster (Crassostrea virginica)

  • Maximum length: 15 cm
  • Colour: reddish-brown or purple
  • Shape: oval
  • Location: Atlantic coast
  • Habitat: brackish and salty waters from 2 to 10 m deep
  • Note: this species is farmed on leased areas of seabed in the Maritimes
olympia oyster

Olympia oyster (Ostrea conchaphila)

  • Maximum length: 9 cm
  • Colour: white to dark purple
  • Shape: oval
  • Location: Pacific coast
  • Habitat: attached to rocks or hard ground in shallow water
  • Note: found in saltwater coves and lagoons and is the only oyster native to the west coast of North America
Pacific Oyster

Pacific oyster (Crassostrea gigas)

  • Maximum length: 30 cm
  • Colour: brown, green or grey
  • Shape: fluted shell with a deep cup
  • Location: Pacific coast
  • Habitat: attached to hard surfaces in shallow water
  • Note: rough shell with sculptured appearance

Scallops

Species of harvested scallops include the following.

Iceland Scallop

Iceland scallop (Chlamys islandicus)

  • Maximum length: 10 cm
  • Colour: grey, reddish-brown or chalk white
  • Shape: fan-shaped
  • Location: Atlantic coast
  • Habitat: offshore areas near Newfoundland at water depths of 50 m to 180 m
  • Note: reddish-pink upper shell and white or cream-coloured lower shell
Sea Scallop

Sea scallop (Placopecten magellanicus)

  • Maximum length: 20 cm
  • Colour: reddish-brown and white
  • Shape: fan-shaped
  • Location: Atlantic coast
  • Habitat: offshore areas including St. Pierre Bank off Newfoundland and Georges Bank off Nova Scotia
  • Note: like all scallops, sea scallops have photoreceptive eyes along their edge
Pink and spiny scallops

Pink scallops and spiny scallops (Chlamys rubida and C. hastata)

  • Maximum length: 8 cm
  • Colour: the spiny scallop is reddish-brown and the pink scallop is pinkish-white
  • Shape: fan-shaped
  • Location: Pacific coast
  • Habitat: offshore areas to water depth of 200 m
  • Note: while spiny and pink scallops are different species, they’re closely related