Lemon sole
Otolith description
Otolith shape is oval and rounded. The sulcus runs over more than half the length of the otolith. The sulcus is open at the ostium, narrow and deep. The sulcus is situated just under the centre of the otolith. The ostium and cauda are well distinguishable and deep. The ostium is longer than the cauda and runs to the margin. Ostium and cauda are separated in a straight sulcus. The surface of the inside is generally smooth but can be irregular around the sulcus. The outside of the otolith is smooth. The margins are rounded with a round pointed end at the ventral posterior side. The rostrum of the otolith is rounded and smaller than in other flatfish species. The inside of the otolith is flat and the outside is slightly concave. The otolith is thick. Otoliths of larger fish (OL>3.5 mm, FL>40 cm) are different from the smaller specimens. The surface along the edges of the sulcus is very irregular in these large otoliths. The rostrum is very pointed and in some cases even a small antirostrum can be visible. Note that these large otoliths of lemon sole will not often be found since fish larger than 40 cm are rare. The otoliths of lemon sole are small in relation to fish length when compared to other flatfish. Otoliths of lemon sole are sometimes difficult to distinguish from otoliths of norwegian topknot Phrynorhombus norvegicus and scaldfish Arnoglossus laterna. The sulcus of lemon sole is longer and deeper and ostium and cauda are better developed than in norwegian topknot otoliths. Also the otolith length-width ratio in lemon sole is larger than in norwegian topknot. Otoliths of scaldfish are more square than are lemon sole otoliths. Sulcus and ostium and cauda are better developed in lemon sole than in otoliths of scaldfish.
The otoliths are rounder and the sulcus is less distinct in eroded otoliths. The thickness of the otolith does not change noticeably.
Otoliths of 0-group lemon sole are oval but more rounded at the margins. The sulcus is hardly visible but ostium and cauda can be seen.
Fish length and distribution
Lemon sole can grow up to 70 cm. Lemon sole is a bottom-living flatfish (MICRKITT.TIF) that can be found on a wide range of bottoms, mud, sand, gravel and rocky grounds. It mainly lives in deeper waters but juveniles can also be found close inshore. (Wheeler, 1978, Nijssen and De Groot, 1987, Witte et al., 1991, Knijn et al., 1993). It spawns from May to October.
Lemon sole is found in the NE Atlantic and North Sea but it is only common locally, especially around banks and rocky shores.
Sample origin
North Sea.