the scallop hauled up on every summer boat trip

Size
Shell: 8–12 cm, Weight: 50–100 g
Lifespan
10–20 years
Diet
Phytoplankton and organic particles. Filters food from the water using its gills. Draws water in through its siphon and extracts microscopic algae. Swims by clapping its shells together to escape predators.
Habitat
Sandy and gravelly bottoms in sheltered bays, harbours and estuaries from 5 to 50 metres depth. Lives on the surface of the seabed. Swims by clapping its shells together to escape predators.
Range
Coastal waters of the North and South Islands from Northland to Stewart Island. Most common in sandy bays and harbours. Endemic to New Zealand. Not found in Australia or elsewhere.
Endemism
Endemic
Main Threats
Commercial overfishing is the primary threat. Habitat damage from dredging. Climate change affecting estuarine habitats and ocean acidification. Water quality degradation in coastal areas.
Population
Populations have declined significantly in many areas due to overfishing and habitat damage. The scallop fishery is managed under New Zealand's quota management system with area closures, size limits and catch limits.
Conservation Status
Not Threatened
One of New Zealand's most prized seafoods, this bivalve has a large, fan-shaped shell beautifully coloured in shades of pink, orange and purple. The colours are produced by pigments in the shell that reflect light in different ways, creating a shimmering effect that changes with the angle of view. A live scallop in the water is a flash of colour against the sand, a jewel of the seafloor. Unlike most bivalves, scallops can swim. They clap their shells together, forcing water out in jets that propel them forward. This swimming ability helps them escape from predators like starfish and octopus. When a starfish approaches, the scallop will clap its shells rapidly, shooting across the seafloor to safety. The swimming motion is not graceful. The scallop flaps erratically, like a butterfly with a broken wing. But it is effective. Most predators cannot keep up. The Maori names Pure and Tipa reflect its importance as a food source. For centuries, Māori gathered scallops from shallow bays, eating them fresh or cooking them in hangi. European settlers recognised the value of the fishery and began commercial dredging in the 19th century. The scallop became a delicacy, served in restaurants and exported overseas. Scallop populations have declined due to overfishing and habitat damage. Bottom dredges dragged across the seafloor scoop up everything in their path, crushing scallops and destroying the seabed habitat. In some areas, scallop beds that once stretched for kilometres have been reduced to scattered individuals. The fishery is now carefully managed. Some areas have been closed to scallop fishing for years to allow recovery. Restoration projects are underway in some regions, with scientists seeding scallops into protected areas in the hope of rebuilding the population. The scallop's many blue eyes are arranged along the edge of its mantle. Each eye has a lens, a retina, and a mirror-like layer that reflects light. The eyes cannot form detailed images, but they can detect changes in light and shadow, warning the scallop of approaching predators. When a shadow falls across the eyes, the scallop swims away. It is a simple system, but it works. To eat a fresh scallop is to taste the clean, cold waters of New Zealand. The flesh is sweet and firm, with a delicate brininess that lingers on the palate. It is a taste of the sea, and it is worth protecting.