Sand eel is the generic term given to small eel-like fish which swim in large shoals and found around the UK, in shallow inshore waters. Sand eels have an elongated body with a pointed head and mouth. A long dorsal fin runs for two thirds of the length of the body, with an anal fin running one third. Pectoral fins are small and low set and the tail fin is forked. The upper body can range in colour from yellowish to black or grey/green, whilst the flanks and underside are silver/white.

Behaviour

Although the adults tend to be very sedentary, never moving far from their burrows, sand eels can be found in large shoals close to the seabed between April and September and will burrow into the sand to escape predators. In the winter months, they bury themselves in sand only emerging to spawn between December and January. Each female sand eel can lay between 3,000 and 15,000 eggs. The larvae hatch between February and April and are transported by currents for up to 7-10 weeks. Very few survive to reach maturity (1-2 years).

Sand eels feed, generally at night, on plankton, and are themselves eaten by a large array of marine life from whales to seabirds, fish to seals. The sharp prominent lower jaw of the sand eel projects further than the upper jaw and when the mouth is opened, the two jaws form a tube through which food is sucked in.

The average lifespan of sand eels ranges from 4-7 years.

Size

Average Length: up to 10-15 cm; max 20 cm (lesser sand eel)

Status

Common; the lesser sand eel is a Priority Species under the UK Post-2010 Biodiversity Framework. Sand eels are a protected feature of three of Scotland’s Marine Protected Areas (MPA): Mousa to Boddam, North-west Orkney and Turbot Bank.

Distribution

Ammodytes tobianus (lesser sand eel) is the most abundant resident species of sand eel found in UK waters. Abundant in Scottish waters, but distribution is patchy and generally concentrated on or nearby sand banks and areas of suitable sediment.

When to see

A wide range of seabirds feed on shoals of sand eels around the Scottish coast. In the spring and summer months, the peak of the breeding season, sand eels provide a staple food for their young. Many sea birds fish explicitly for sand eels and can be seen carrying a mouthful of these fish back to their nests.

Facts

• There are five species of Sand eels found in UK waters. In addition to the lesser sand eel, the greater sand eel (Hyperoplus lanceolatus) also lives close to the shore and is the most likely to be caught by anglers. The three other species, the smooth, Raitt’s and Corbin’s Sand eels are deeper water species which rarely come close to land. 

• Sand eels are vitally important in the marine food chain in Scottish waters, providing a source of food for a wide range of other species. Populations of guillemots, razorbills, puffins and kittiwakes have been found to decrease when sand eel abundance declines. A number of measures, such as closing areas to sand eel fishing, have helped to increase sand eel populations in turn increasing local seabird populations and their breeding success.

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