Pilchard
Otolith description
The general shape of the otolith is ovally pointed. The sulcus is straight and runs over the whole length of the otolith and is open at both sides although this is not very clear at the posterior. The sulcus is not well developed and ostium and cauda can not be distinguished. The surface of the sulcus is smooth and a bit thicker at the outer margin of the sulcus. The surface of the inside is smooth, whereas the margins are a bit irregular. The anterior margin is indented at the ostium. The posterior end is rounded and at an angle of more than 90° with the ventral side. The outside of the otolith is smooth. The rostrum of the otolith is well developed and pointed and there is also a large pointed antirostrum. The otolith is thin and flat at both sides. Otoliths of pilchard do not exceed 4.5 mm.
Pilchard otoliths are difficult to distinguish from other clupeiformes, particularly with herring Clupea harengus that also has a long rostrum. Herring otoliths have a sulcus that is better developed and a posterior end at about 90° with the ventral side of the otolith. The rostrum of herring otoliths is smaller and less pointed. The posterior end is not indented but rounded in pilchard otoliths. The otoliths of sprat Sprattus sprattus have a rounded rostrum and the posterior end is indented and more pointed compared to pilchard otoliths. The otolith length-width ratio is smaller in sprat otoliths. Otoliths of twaite shad Alosa fallax often have between the rostrum and antirostrum another protruding element, and the rostrum is more rounded than in pilchard otoliths. Anchovy Engraulis encrasicolus has a closed sulcus which ends at the centre of the otolith. The rostrum is more pointed but less developed than in pilchard otoliths.
When eroded the sulcus becomes less distinct and the margins, rostrum and antirostrum are smoothed. Often the rostrum is missing after the otolith has gone through the digestive tract of an animal.
Fish length and distribution
Pilchard can grow up to 25 cm. Pilchard is a pelagic, schooling roundfish (SARDPILC.TIF) that is mostly found in inshore waters. It is not as common in the northern and central North Sea as herring and sprat, eggs and larvae are abundant in the Southern North Sea but they do not survive. It spawns in spring and summer in the open sea (Wheeler, 1978, Nijssen and De Groot, 1987, Muus et al., 1999).
Pilchard is found in the Atlantic coastal waters of Southern Europe, The Channel and the North Sea.
Sample origin
Southern North Sea and Channel.