Mackerel
Otolith description
The shape of the otolith is ovally pointed. The sulcus runs almost straight over the total length of the otolith and is strongly curved at the cauda. The sulcus is open at the ostium and in some specimens also open at the cauda. The sulcus is wide and deep. The ostium is wider than the cauda. The surface of the inside, except for the edges of the sulcus, and outside are smooth. The rostrum is well-developed and pointed. The antirostrum is smaller than the rostrum but also pointed. The ventral margin is straight while the dorsal margin is pointed and slightly lobate. The posterior margin is pointed. The inside of the otolith is convex and the outside concave. The otolith is thin and very fragile and often lost in diet samples.
When eroded the sulcus and rostrum remain visible, but the rostrum is often broken off after the otolith has gone through a digestive tract of an animal. The dorsal margin of the otolith is smoothed when eroded.
Fish length and distribution
Mackerel can grow up to 66 cm. Mackerel is a pelagic, predatory schooling fish (SCOMSCOM.TIF) found both in inshore and offshore waters. In winter it is inactive and found close to the bottom. It is a migratory fish found in the Northern waters only in summer. Spawning in the North Sea takes place from May to August (Wheeler, 1978, Nijssen and De Groot, 1987, Knijn et al., 1993, Muus et al., 1999).
Mackerel is a very common fish found in the Northern Atlantic, North Sea and Baltic.
Sample origin
Fyke, Southern North Sea and Celtic Sea.