Shellfish in the Sea

Clams
Butter, littleneck, Manila, razor and geoduck clams are all found in Vancouver Island waters.

Butter clams are common to protected beaches in bays and estuaries along the coast. The habitat of the butter clam is typically beaches of porous sand, broken shell, gravel and mud and they may occur in association with littleneck clams. Butter clams burrow to a maximum depth of 25 centimetres and adults remain in the same burrow for life. Butter clams are suspension feeders and eat mainly phytoplankton, but also zooplankton and detritus. Crab and fish prey on young clams and moon snails, birds and sea stars prey on adults. Butter clams sexually mature at 38 millimetres or about three years. The legal size of 63 millimetres is reached in five to six years in the Strait of Georgia and seven to eight years in Alert Bay, off the north coast of Vancouver Island.

Littleneck clams are also common to protected beaches, in bays and estuaries along the coast, but also near rocky outcrops on outer coasts. They live in firm, gravel beaches and sometimes coexist with butter clams. Littleneck clams burrow to a maximum depth of 15 centimetres, but usually three to eight centimetres below the surface. Like he butter clams, adults remain in the same burrow for life, are suspension feeders and eat phytoplankton, zooplankton and detritus and crabs and fish prey on juveniles, while moon snails, birds and sea stars prey on adults. Littleneck clams sexually mature at 25 millimetres or about two years. The legal size of 38 millimetres is reached in 3.5 years in the Strait of Georgia.

Manila clams are an exotic species. They are common to protected beaches, in bays and estuaries in Georgia Strait and the west coast of Vancouver Island. Manila clams live in sand-gravel beaches and burrow just below the surface to a maximum depth of approximately 10 centimetres. Adults remain in the same location for life. Manila clams are suspension feeders and eat mainly phytoplankton, but also zooplankton and detritus. Manila clams are preyed upon by water birds. These clams are sexually mature at 20 millimetres or about two years. The legal size of 38 millimetres is reached in 3.5 years in the Strait of Georgia.

Razor clams only occur only on the sandy, exposed beaches of the Long Beach region on the west coast of Vancouver Island. They burrow from just below the surface to a depth of 25 centimetres, but can burrow to depths greater than 60 centimetres in less than a minute. Razor clams do not form permanent burrows. They are filter feeders and eat mainly planktonic diatoms, but also zooplankton and detritus. Gulls, ducks, crabs and fish prey on the razor clam. Razor clams sexually mature after one year in the south and three years in the north. The minimum legal size of 90 millimetres is reached in one to two years at Long Beach. The largest and oldest clams found in BC were from the Queen Charlotte Islands.

The geoduck clam is the largest clam in BC. It is widespread, in sheltered to moderately exposed brackish or outer coastal areas. It lives in fine mud, sand or gravel and may be abundant in eelgrass. It burrows up to one metre and adults create a semi-permanent burrow. Geoducks are suspension feeders and mainly eat phytoplankton, but also zooplankton and detritus. Sea stars, crabs, fish and birds prey on the geoduck. Geoducks sexually mature by three years of age and reach 16 centimetres in 10 years; there is little change in length in its remaining years. Geoducks may weigh up to 4.5 kilograms and have been recorded as old as 146 years.

Crab
Crabs, including Dungeness crab, are common and widespread in sandy areas along the coast. They may also occur in mud and gravel and are often buried just below the surface of the sand or in vegetation. Young crabs remain in intertidal and shallow waters hiding among plants, rocks and shell debris until their second summer. Breeding occurs in inshore waters and females may move to deeper water to hatch their eggs.

Crabs eat bivalves, crustaceans, marine worms and fish. Their predators include octopuses, halibut, dogfish, sculpins, rockfish, birds and larger crabs. Crabs must molt to grow; females and males sexually mature at 100 and 150 millimetres respectively, or at two to three years. Males reach legal size (165 millimetres) at three to four years and females seldom reach legal size.

Octopus
Octopuses occur in rocky areas throughout the BC coast. They establish dens in these rocky areas or caves, or smaller individuals may dig dens in sand-shell substrates. Females brood eggs on the roof of the den. Octopuses inhabit deep water from February to April and August to October. The octopus is a nocturnal predator; larvae feed on copepods and other zooplankton; juveniles and adults prey on crabs, cockle, littleneck clams, abalone, moon snails and small fish. Predators of the octopus include seals, sea lions, sea otters, dogfish, lingcod, flatfish and larger octopuses. Octopuses sexually mature at two to three years, males after 12 kilograms and females after 20 kilograms. At one year old, octopuses weigh 1 kilogram and after a year and a half weigh 12 kilograms. The largest octopus recorded weighed 272 kilograms with a total arm spread of 9.6 metres.

Prawn
The prawn is 253 millimetres (10 inches) in length and has prominent white spots on both sides of the first and fifth segments of its abdomen. At times, juveniles have been observed on muddy bottoms, but adults normally live in rocky crevices and under boulders. The prawn ranges throughout the northern Pacific from Unalaska to San Diego and from the Sea of Japan to the Korea Strait. Commercial trap fishing is carried on all along the British Columbia coast. The prawn is male during its second and third years, then changes sex in the third or fourth year. Eggs are found on females from October to March.

Scallop
The scallop is discontinuous along the coast and may exist in small, high-density beds. The habitat of the scallop is a sand or mud bottom in areas with a strong current. Adults attach to rocks and may move by swimming to a new location and re-attaching. Scallops are suspension feeders and mainly eat phytoplankton, detritus and zooplankton. Predators of the scallop are sea stars, snails, fish, boring worms and sponges. The maximum growth of a scallop is 85 millimetres, reached in four to five years, and they sexually mature at 60 millimetres or two to three years.

Sea Cucumber
The sea cucumber is common and widespread along the BC coast. It is most common on bedrock in areas with little or no current, where detritus accumulates. It also lives in gravel, sand or mud, and often in eelgrass beds. Larvae and juveniles hide in dense mats of filamentous red algae, algae holdfasts, under rocks or in rock crevices. Spawning occurs in shallow water, less than 16 metres deep. Sea cucumbers are deposit feeders and eat organic matter and associated microorganisms. Sea stars prey on adults and larvae have numerous predators. Sea cucumbers are five to 20 millimetres long at one year and reach a maximum size of 500 millimetres. They take five to six years to reach sexual maturity and live to over eight years.

Sea Urchins
Red and green sea urchins occur in rocky areas throughout exposed and protected coastal waters. They live in ledges and crevices, giant or bull kelp beds and other brown algae in areas of moderate to swift currents. Larvae drift and feed in plankton. Juveniles settle near kelp beds and often associate with adults and remain under adult spines until they reach 40 millimetres. Sea urchins are herbivores and graze on attached marine plants and drifting kelp fragments. Their primary food is kelp and they may limit kelp distribution. Predators of the sea urchin include sea stars, sea otter, octopuses, crabs and wolf-eels. The red sea urchin is very dependent on its food supply and sexually matures at a diameter of 50 millimetres  at around two years. It reaches its commercial size of 100 millimetres at four to five years and may reach 190 to 200 millimetres. The green sea urchin reaches an average size of 50 to 60 millimetres, but may reach a maximum size of about 85 millimetres.

Shrimp
Species of shrimp include dock, humpback, pink and sidestripe.

The dock shrimp (coonstripe) is named for its habit of living around docks. The irregular brown and red striping on the abdomen of the dock shrimp gave rise to its other name: coonstripe. The dock shrimp also inhabits sand or gravel bottoms, usually where a rapid tidal current flows. It ranges from Sitka, Alaska to near San Diego, and a productive trap fishery is carried out in Sooke Harbour, west of Victoria. Dock shrimp reach lengths of 140 millimetres (5.5 inches). Shrimp of this species function as males during the first and second years, and as females in their second and third years. Some individuals mature first as females, never functioning as males. Females with eggs may be found year-round, but the main breeding season is from November to April.

The humpback shrimp (king) is characterized by a crest or hump on its head. It has wide, irregular, reddish bands on its body, white and reddish bands on its legs and white spots on its carapace. Its total length is 192 centimetres (7.5 inches). The humpback occurs in the Bering Sea from the Aleutian Islands to Puget Sound, and in the Ohkotsk Sea as far south as the Korean Strait. This species attains maturity as a male, in varying proportions as a female in the second year, and becomes a female during the third year. Survival into the fourth year is very low. Female shrimp carry eggs from November to April.

The pink shrimp (smooth) is a uniform colour and measures 175 millimetres (6.9 inches) in total length. Distribution of this species ranges from Unalaska to near San Diego. Local trawling grounds lie along the continental shelf off Tofino and Nootka Sound, in Barkley Sound, and along the east coast of Vancouver Island. This shrimp, now in second place commercially, was the most valuable shrimp species landed from 1960 to 1978. Maturation as a male occurs during the second year, with sex change taking place in the following year. In the Strait of Georgia, it is known that as many as 40 per cent of an age group may mature first as females. The egg-bearing period extends from November to April.

The sidestripe shrimp has a pale orange body with pale horizontal bars. It reaches lengths of 208 millimetres (8.2 inches) and has extremely long antennae. The sidestripe occurs in the north-eastern Pacific Ocean from the Bering Sea to the Oregon coast. In British Columbia, it is caught by trawl in English Bay, Howe Sound, Stuart Channel, Barkley Sound and Chatham Sound, but it rarely enters baited traps. It is generally found on muddy bottoms at depths of 90 to 201 metres. Maturity as a male is attained during its second year; a sex change occurs in the third year, with relatively few females appearing to survive into the fourth year. In the Strait of Georgia, females carry eggs from October to March.

Squid
Squid are common in offshore coastal waters but move inshore to spawn. They spawn in sheltered locations over a mud or sand bottom in water depths of three to 40 metres. Juvenile squid feed in the upper 15 metres of water and are dispersed by currents. They move offshore as they grow. The squid is a predatory carnivore. Newly-hatched larvae feed on tiny crustaceans in the plankton and juveniles prey on fish, crustaceans and smaller squid. Salmonids, flatfish, other fish, sharks, marine mammals and sea birds prey on squid. Sexually maturity is reached by squid at one year. The maximum length of a squid is about 175 millimetre and adults weigh 14 to 70 grams.