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Photo: Øivind Strand
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Great scallop

Common along the coasts of the north-eastern Atlantic Ocean from the Iberian peninsula in the south to Vestfjorden in the north. Found on sandy bottom from just below the intertidal zone and down to depths of more than 100 m. In Norwegian waters they are most common at depths of 5-30 m in the counties of Sør-Trøndelag, Nord-Trøndelag and Nordland.

Scallops normally recess in the seabed sediments with their flat valve facing upwards, flush with the sea bottom and covered by sediment.

They are generally found in areas with strong currents, on a variety of seabed types, ranging from fine to coarse gravel, which may or may not be mixed with mud and organic matter. They feed on phytoplankton, bacteria, other micro-organisms and dead organic matter (detritus). Their most important sources of food are phytoplankton and microscopic algae found on the seabed substrate. The water currents supplies the food particles, and in many places factors such as the depth, tides and topography will affect variations in their access to food. Seasonal fluctuations in phytoplankton production also cause great variation in both the quantity and quality of nutrition available to the scallops. The distribution of great scallops in Norwegian waters is significantly limited by low winter temperatures and salinity. Climate change accompanied by milder winters may therefore explain the extension of their distribution northwards that is seen in the Lofoten islands. Scallops have low tolerance of reduced salinity, and any change in the amount of fresh water entering coastal waters may also affect their distribution along the coast.

Facts about great scallop

Latin name: Pecten maximus
Family: Pectinidae
Lifespan: over 20 years. Shell height: 17-18 cm. Maximum weight: 500-600 grammes.
Habitat: lives in recesses in seabed sediments, partially covered by sediment.
Spawning area and season: Spawns during the summer. Fertilisation takes place in the open water where the larvae develop and settle on the bottom after more than a month.
Feeding habits: diet consists of phytoplankton, bacteria, other micro-organisms and dead organic material. 

Status and recommendations

In Norway, the great scallop are only harvested by divers, with the core area for the fishery being in Trøndelag county. The Institute of Marine Research carry out regular surveys to determine recruitment and age structure of the stocks.

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Map of distribution

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