The general shape of the otolith is ovally rounded. The sulcus runs over 2/3 of the total length of the otolith. The sulcus is open at the ostium. The ostium is clearly visible, but the cauda is indistinct. The ostium is deeper and wider than the cauda. When visible the cauda runs slightly dorsally from the ostium. The surface of the inside and outside and the margins are smooth. The margins are rounded, though the posterior end tends to be pointed in some specimens. The rostrum is visible and rounded. The antirostrum is indistinct. The inside is convex, the outside is slightly concave. The otolith is thick. Otoliths do not exceed 4 mm in length.
Otoliths of ammodytidae, sandeel, Raitt’s sandeel Ammodytes marinus and greater sandeel Hyperoplus lanceolatus, are very difficult to identify to species level. The posterior end of sandeel otoliths tends to be slightly more pointed than in the other species. The rostrum of Raitt’s sandeel tends to be more pointed compared to other ammodytidae. The sulcus of greater sandeel tends to be slightly wider and the posterior end tends to be slightly lobate. The above features are all variable and the variation between the species is a large as within the species. Size can help to separate the larger greater sandeel; otoliths > 4 mm are always of greater sandeel. Otoliths of both sandeel and Raitt’s sandeel can reach 4 mm in length.
When eroded the sulcus becomes indistinct. Because of the thickness of the otolith, the general shape remains ovally rounded.
Otoliths of juvenile sandeel already have the ovally rounded shape, but there are indentations visible at the ventral and dorsal margin.
Fish length and distribution
Sandeel can grow up to 20 cm. Sandeel is a demersal schooling fish (AMMOTOBI.TIF) found in coastal waters. It is often buried in clean fine sand, but can also be found in schools at the surface. Two spawning races are recognised, a spring spawning stock and an autumn spawning stock (Wheeler, 1978, Nijssen and De Groot, 1987, Witte et al., 1991, Muus et al., 1999).
Sandeel is a very common fish found in the coastal waters of the NE Atlantic, North Sea and Baltic.
Southern North Sea and some from the Western Wadden Sea.