Four-bearded rockling
Otolith description
The shape of the otolith is triangular. The sulcus is well developed and open. The ostium and cauda are both wedge shaped and the sulcus is parted between the ostium and cauda. The surface of the inside and margins are irregular, while the outside is smooth. The rostrum is visible and rounded. The antirostrum is small and rounded and can be indistinct in some specimens. The posterior margin is pointed. The inside of the otolith is convex and the outside concave. The dorsal margin is rounded, while the ventral margin is almost straight. The otolith is thin. Otoliths of rocklings are small and fragile compared to otoliths of other gadidae and do not exceed 5 mm in length.
Otoliths of four-bearded rockling are hard to distinguish from five-bearded rockling, particularly when eroded. The otolith length-width ratio is much bigger in five bearded rockling. Otoliths of five-bearded rockling tend to be more concave at the outside. The rostrum of five-bearded rockling otoliths is far more distinct (but breaks off easily) and more rounded. Otoliths of four-bearded rockling may also be confused with those of dragonets callionymidae, which are also small and triangular but thicker. Otoliths of callionymidae also have a wedge shaped ostium, but the cauda is indistinct. Otoliths > 4 mm in length are always of four-bearded rockling.
When eroded the ostium and cauda remain visible. The inside and margins are smoothed. Rockling otoliths are fragile and are often broken when gone through the digestive tract of an animal.
On otoliths of juvenile four-bearded rockling the sulcus is hardly visible. The rostrum and posterior end are round. The otolith is already triangular shaped.
Fish length and distribution
Four-bearded rockling can grow up to 41 cm. Four-bearded rockling is a bottom-living fish (RHINCIMB.TIF) found on sandy or muddy grounds, in depths from 20 to 250 m. In its northern range it is found more in shallower waters. It spawns in late spring and summer in deeper waters (Wheeler, 1978, Nijssen and De Groot, 1987, Witte et al., 1991, Knijn et al., 1993, Muus et al., 1999).
Four-bearded rockling is found in the Northern Atlantic, North Sea and Baltic.
Sample origin
Southern North Sea.