Sole
Otolith description
Otolith shape is square. The sulcus runs over more than half the length of the otolith and is closed or sometimes open at the ostium. The sulcus is narrow and slightly deepened. Ostium and cauda are not distinguishable. The surface of the otolith is irregular and the margins are smooth. The posterior end of the otolith is straighter than the other margins. The rostrum of the otolith is rounded. The inside of the otolith is slightly convex. The outside of the otolith is concave, distinguishing this species from other soleidae which are flat or convex. Otoliths of sole are comparatively thin, those of other soleidae being much thicker.
Eroded otoliths are rounder instead of square. The sulcus is less distinct. The surface of the otolith will be smoother with progressed erosion.
Otoliths of 0-group flatfish are also square but hard to distinguish from other juvenile flatfish. The sulcus is only just visible.
Fish length and distribution
Sole can grow up to 60 cm. Sole is a bottom-living flatfish (SOLEVULG.TIF) that is common on sandy and muddy grounds. Sole is active during the night and although it is mainly a bottom-living fish it can also be found near the surface at night. Adult sole are generally found in deeper water whereas juveniles are found in the tidal zone (Wheeler, 1978, Witte et al., 1991, Knijn et al., 1993). Spawning occurs from April to May (Knijn et al., 1993).
Sole can be found in the NE Atlantic Ocean, North Sea and Baltic.
Sample origin
Juvenile fish: Fyke and western Wadden Sea.
Adults were caught in the southern North Sea.