Username: Password:   Mandate   Objectives   Environmental Policy   Oyster   Mussel   Finfish   R&D priorities   R&D Coordinator   R&D funding agencies   Species   Health & Nutrition   Benefits of Eating Finfish   Benefits of Eating Shellfish   Market Forms of Seafood   Grades of Oysters   Buying Fresh Seafood   Basic Cooking Methods   Recipes   Care & Storage of Seafood   Sources & References   Species Information The following species are grown in aquaculture settings on PEI. Mussels Easily recognized by its dark bluish black colour the blue mussel (Mytilus edulis) is a shellfish bivalve belonging to the Mytildae family. Mussels are hardy fast growing estuarine species making them ideal candidates for aquaculture. Like most bivalves they have two equal valves or shells held together at the hinge by a rubbery ligament called a resilium. Mussels, like all bivalves, are filter feeders, filtering microscopic phytoplankton and zooplankton from the water using their gills. Sexes are separate for most bivalves including mussels, oysters and clams. Once fertilized, the eggs develop into a trocophore larvae (50-70 µm). Over the next 24-36 hours the larvae develop into a Veliger larvae (70-110 µm) which has a velum or swimming organ. The Veliger forms a mouth and a minute shell gland, which, eventually develops into the two calcified valves that will envelope and protect the soft-tissues of the mussel throughout its life. This is followed by a pediveliger stage in which a foot develops. The larvae disperse through wind and tidal currents. After 7-14 days, the larvae will settle on various substrates (gravel, wharfs, rocks, etc.). Mussels cling to various substrates by byssal threads or their "beards." This trait makes them easy to grow from ropes or socks held in suspension from buoyed lines in the water column. On PEI, it typically takes 18-24 months to reach a market size of 55-60 mm. PEI mussels are sold fresh or frozen virtually world-wide and are recognized in markets and restaurants from Asia, Europe and all over North America. Atlantic Salmon The Atlantic Salmon (Salmo salar) is an anadromous (sea run) fish belonging to the Salmonidae Family. Adults are silver in colour and have an elongated, laterally compressed body with a large mouth, fairly large scales, and a fleshy adipose fin on the back just in front of the tail fin. It spawns in freshwater streams with the adults returning to the sea while the young remain for 2 to 3 years. When the young fish (smolts) are about 15 cm in length they migrate to sea where they may live one or more years before returning to fresh water to spawn. Salmon start off as pea-sized orange coloured eggs, evolving into alevin (2 cm long) or sac fry. During this period the alevins utilize their attached sac for food. Feeding is normally initiated when the sac is almost completely absorbed. Once feeding has begun, they are referred to as fry (5-8 cm long). The next stage of development is characterized by dark backs and bar marks on their sides acting as camouflage. They are now referred to as Parr. At 12-24 cm long, Parr undergo a springtime transformation into Smolt. This physiological change allows the young salmon to tolerate saltwater and thus migrate to the sea. An average adult weighs anywhere from 2-10 kg or much larger. The average length of the salmon is 50-100 cm. Because the Gulf of St. Lawrence becomes frozen in the winter, Salmon aquaculture is limited to land-based operations. As a result, salmon aquaculturists on PEI specialize in the egg to fry market. Oysters The American or Eastern oyster (Crassostra virginica) has a long history of production on PEI with bottom culturing techniques for oysters dating back to the 1800’s. It is a bivalve mollusc of the Ostreidae family. PEI is home to the famous Malpeque oyster (Malpeque Bay) that was judged tastiest oyster in the world and won the highest award at the Paris Exhibition in 1900. PEI oysters typically have a distinct saltier taste than their other North American counterparts. Oysters shells are variable in shape with a brown, grey, green or white colour. As a result, oysters are graded into Fancy, Choice, Standard and Commercial grades based on the length to width ratio. The most desirable oyster has an oval to almost round shape with its left (bottom shell) valve forming a nice cup on which the oyster is served. Oysters are fished on public grounds are cultured on bottom, in mesh bags attached to tables or trays or in floating mesh bags anchored to longlines. It typically takes two to three summers for cultured oysters to reach the market size of 75 mm on PEI. Arctic Charr Arctic Charr (Salvelinus alpinus) exist as both an anadromous (sea run) and resident fresh water population species. They have an elongated body, an adipose fin, very small scales and an easily distinguished skull structure. Anadromous Charr are silvery in colour with tints of deep to greenish blue on the back and sides with red to pinkish spots along and below the lateral line. Freshwater or land locked Charr are green-brown with reddish to white spots along the side and an orange to red belly. Anadromous species reach 2 to 7 years old before migrating to the sea for the first time. In Labrador, anadromous females do not sexually mature until 6 years of age. Arctic Charr are not native to PEI and their culture is a recent undertaking on the Island. Charr are raised from egg to fry in land-based hatcheries, typically, to a market size of 2 to 4 pounds (40 to 50 cm long). Rainbow Trout Rainbow trout (Oncorhynchus mykiss) is and anadromous fish with a characteristic salmon-like head. Their back is usually a dark olive colour, shading to silvery white on the underside. They are called rainbows because of their crimson lateral stripe and rainbow colours mainly found during the spawning months. Males during spawning time can become very dark. Females are called hens and males are called bucks. Males are easily distinguished by the large hook or "kype" on the lower jaw. This is characteristic of all male salmonids. The head and body are heavily marked with small black spots mainly on the upper body as well as top and tail fins. Brown trout do not have spots on the tail. Rainbow trout will lay their eggs in shallow nest in the gravel. After 21 days the eggs will hatch. At about one year of age the fish are known as 'fingerlings' and at two years they become sexually mature but often mate at three years of age. Rainbow trout are carnivores feeding on a variety or prey including insects, crustaceans, molluscs and fish. In North America, rainbows with access to the sea have been recorded in excess of 42 pounds. The confined or cultured record is 31.27 pounds. On PEI, as with Atlantic salmon and Arctic charr, rainbow trout are cultured in land-based facilities. A typical market sized cultured Island rainbow starts at 1 ¼ pounds and goes up from there. Soft-shell Clams The soft-shell clam (Mya arenaria) often called the "steamer" or "squirt clam" and belongs to the Myacidae family. Unlike mussels or oysters, clams live buried in the sand or mud, below the mid-tide level. It gets its name as it squirts water from its hole when disturbed. This estuarine bivalve has thin, relatively brittle chalky white shells or valves. Unlike mussels or oysters, soft-shell clams cannot completely close their shells because of their long siphons used to filter water. Soft-shell clams were used as food by First Nations people before the arrival of Europeans. The latter used them as fish bait in the mid-1800's and by the end of the 19th century, clams had become widely accepted as a seafood delicacy on both coasts of Canada. In Atlantic Canada, this species is sold live for steaming or battered, deep fried and served with fries (clams and chips). Aquaculture practices with soft-shell clams typically involve relaying seed (juvenile) clams from public beds to leased sites for on bottom growout. A market size of 50 mm can usually be reached on PEI in approximately two years. Quahaugs (Hard-shell clams) Quahaugs (spelled quahog in the US) or hard-shelled clams (Mercenaria mercenaria) have a tough, thick, predator resistant shell. They are members of the Veneridae family of bivalves. Smaller quahaugs, less than 50 mm are called Littlenecks, while 50-75mm clams are called Cherrystones. Quahaug aquaculture involves relaying juvenile clams from public beds or purchasing hatchery reared seed for bottom growout on leased water. Quahaugs are typically used for seafood chowders owning to their toughness, but smaller clams may be eaten on the half shell. In the 1960’s a striped variety called the "notata" quahaug (M. mercenaria notata) was selectively bred in a Massachusetts hatchery and developed on PEI in the late 1980’s. Notata variety quahaugs have distinctive zigzag striped marking rarely encountered with their wild counterpart. One out of every 1000 wild quahaugs have the notata markings. Market size wild variety quahaugs grown in PEI can be achieved in four to five years, typically faster (3 years) with the notata variety.