Black goby
Otolith description
Otoliths of gobiidae are all very similar in shape and are hard to identify to species level. The shape of black goby otoliths is square. The sulcus is closed and runs diagonally. The ostium is slightly wider than the cauda. The cauda sits dorsally from the ostium. The surface of the inside, the outside and margins are smooth. There is a small rostrum visible, which is rounded. The antirostrum is indistinct. The posterior margin is lobate, often with a large lobe at the dorsal side. The dorsal margin is rounded, while the ventral margin is straight. The inside of the otolith is flat and the outside convex. The otolith is thick. Otoliths of black goby are the largest of the gobiidae. Otoliths >3 mm in length are always of black goby.
Otoliths of gobiidae are all very similar. Otoliths of transparent goby Aphia minuta and crystal goby Crystallogobius linearis are round instead of square and the inside of these otoliths is convex. In transparent goby the cauda is indistinct. On otoliths of crystal goby the whole sulcus is indistinct. Otoliths of common goby Pomatoschistus microps have an antirostrum, almost the same size as the rostrum. The rostrum of painted goby P. pictus is not as well-developed as in other gobiidae otoliths. Sand goby P. minutus otoliths also have a distinct antirostrum which is lobate. Otoliths of Lozano’s goby P. lozanoi do not have a well-developed rostrum and the posterior end is only slightly lobate or round.
When eroded the above described differences disappear and are therefore not useful for identifying otoliths to species level. Eroded gobiidae otoliths are round with the sulcus slightly visible.
There is some difference in the maximum size of the fish and therefore in the otoliths:
crystal goby: <0.7 mm
transparent goby: <1.5 mm
common goby, Lozano’s goby: <2.0 mm
painted goby: <2.5 mm
sand goby: <3.0 mm
black goby: >3.0 mm
Fish length and distribution
Black goby can grow up to 17 cm. Black goby is a bottom-living fish (GOBINIGE.TIF) found on muddy and sandy bottoms. It is found in estuaries and brackish waters, in depths up to 50 m. Spawning takes place from May to August (Wheeler, 1978, Nijssen and De Groot, 1987, Muus et al., 1999).
Black goby is a common fish found in estuaries of the NE Atlantic, North Sea and Baltic, but is absent from the Wadden Sea.
Sample origin
SW Netherlands.