Agonus cataphractus


Otolith description
The general shape of the otolith is oval, either rounded or pointed. The sulcus runs slightly diagonally over 2/3 of the length of the otolith. The sulcus is clearly visible and open or nearly open at the ostium. Ostium and cauda are separated by a narrowing of the sulcus. The otolith has a rough texture. The surface of the inside and sulcus is irregular, while the outside surface is smooth. The ventral margin is straight or slightly rounded, but smooth. The dorsal margin is rounded and smooth. The rostrum is round. The antirostrum is often indistinct, and when visible small and rounded. The anterior margin is slightly indented between the rostrum and antirostrum in most specimens. The posterior margin is pointed. The inside is convex and the outside concave. The otolith is thick. Otoliths are not longer than 6 mm.
When eroded the sulcus remains visible and becomes wider. The surface becomes smooth and the posterior end more rounded. It can be difficult to distinguish eroded hooknose otoliths from bull-rout Myoxocephalus scorpius. The sulcus of hooknose otoliths is wider compared to bull-rout. The length-width ratio in hooknose is smaller than in bull-rout otoliths.
Juvenile hooknose otoliths are more round than oval shaped. The sulcus is indistinct. The surface of the otolith is smooth as is the posterior end.
Hooknose has a two pairs of strongly curved, hooked spines on the snout. These are also often found in samples.

Fish length and distribution
Hooknose can grow up to 20 cm. Hooknose is a bottom-living fish (AGONCATA.TIF) found in inshore waters on rocky, sandy or muddy bottoms. Juveniles are pelagic. It spawns from February to May and the eggs are deposited between the holdfasts of kelp or other algae (Wheeler, 1978, Nijssen and De Groot, 1987).
Hooknose is a common fish found in the NE Atlantic, North Sea and Baltic.

Sample origin
Southern North Sea and Western Wadden Sea.