Dab
Otolith description
Otolith shape is oval and rounded. The sulcus runs over more than half the length of the otolith and is closed. The sulcus is narrow, deep and straight. Ostium and cauda are clearly visible, deep and separated. The ostium is sometimes longer than the cauda. The surface of the otolith is smooth. The surface around the sulcus is thicker than the surrounding area. The margins are straight. Sometimes at the posterior end a sharp point is visible. The rostrum of the otolith is rounded, but more pointed than in otoliths of plaice Pleuronectes platessa. The inside of the otolith is slightly convex. The outside of the otolith is flat, distinguishing this species from other pleuronectidae. Otoliths of dab are thick.
Eroded otoliths are often difficult to determine to species level. The sulcus of eroded otoliths becomes less deep. When otoliths are eroded the sulcus remains longer visible in otoliths of dab than in plaice otoliths. With progressed erosion the general shape of the otolith becomes more triangular instead of oval.
Eroded otoliths of 0-group flatfish are not distinguishable with great certainty. Small otoliths are rounder. In small otoliths the sulcus is visible and the ostium and cauda are distinguishable.
Fish length and distribution
Dab can grow up to 42 cm. Dab is a bottom-living flatfish (LIMALIMA.TIF) found on sandy grounds. It is very abundant in the North Sea. Dab is mostly found in shallow areas and moves inshore in summer. Juvenile fish are found in the Southern North Sea (Wheeler, 1978, Witte et al., 1991, Knijn et al., 1993). Spawning occurs from January to August (Muus et al., 1999).
Dab can be found in the NE Atlantic, North Sea and Baltic.
Sample origin
Fyke and western Wadden Sea. Larger fish were also caught in the southern North Sea.