Turbot
Otolith description
Otolith shape is square with a rounded dorsal margin. The sulcus runs over more than half the length of the otolith. The sulcus is open at the ostium and narrow. Ostium and cauda are distinguishable and separated by a slight narrowing of the sulcus. Ostium is longer, wider and deeper than cauda. The surface of the inside is smooth and irregular on the margins. The margins are jagged especially ventrally. In some specimens a small indention at the posterior end is visible. The outside of the otolith is smooth. The rostrum of the otolith is rounded and a small rounded antirostrum is visible in fresh otoliths. The otolith can be indented between rostrum and antirostrum in some specimens. The inside of the otolith is convex and the outside concave. The otolith is thin.
Turbot otoliths are difficult to distinguish from other bothidae such as brill Scophthalmus rhombus and megrim Lepidorhombus whiffiagonis. Otoliths of brill are lobate at the ventral margin, but when otoliths are eroded the margins are smoothed in both turbot and brill. The sulcus of turbot is longer and the ostium is deeper than the cauda whereas in brill the cauda is deeper. Otoliths of megrim are generally rounder and thicker than turbot otoliths. The sulcus of megrim otoliths is not as deep as on turbot otoliths, but when eroded the sulcus becomes less distinct in both species. Otoliths with lengths >5 mm are always from brill or turbot and never of megrim.
Eroded otoliths have smooth margins. The sulcus and antirostrum become less distinct with progressed erosion.
The otoliths of 0-group turbot, brill and megrim are not distinguishable. Otoliths of 0-group turbot are more squared and somewhat indented at the ostium. The surface and margins are smooth.
Fish length and distribution
Turbot can grow up to 100 cm. Turbot is a bottom-living flatfish (PSETMAXI.TIF) that is found on gravel and sandy bottoms at depths up to 80 m. Juveniles are found in less deep water, the smallest even into the surf zone (Wheeler, 1978, Witte et al., 1991, Knijn et al., 1993). It spawns from April to August (Muus et al., 1999).
Turbot is found in the Eastern Atlantic, Southern North Sea and Baltic.
Sample origin
Juveniles: Fyke.
Adults: North Sea.