Sand goby
Otolith description
Otoliths of gobiidae are all very similar in shape and are hard to identify to species level. The shape of the otolith is square. The sulcus is closed and diagonally. The ostium is slightly wider than the cauda. The cauda is dorsal 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 small and rounded. The posterior and anterior margins are lobate. The dorsal margin is rounded, while the ventral margin is straight, giving the otolith the shape of a cumulus cloud. The inside of the otolith is flat and the outside convex. The otolith is thick. Otoliths of sand goby do not exceed 3.0 mm in length.
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 the otoliths is convex. In transparent goby the cauda is nearly invisible. On otoliths of crystal goby the whole sulcus is indistinct. Otoliths of black goby Gobius niger, common goby Pomatoschistus microps, painted goby P. pictus and Lozano’s goby P. lozanoi all have a rostrum with or without an antirostrum, but the anterior side of the otoliths is not lobate like in otoliths of sand goby.
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
Sand goby can grow up to 10 cm. Sand goby is a common fish (POMAMINU.TIF) found in coastal waters and estuaries, in depths up to 40 m. It is mostly found on sandy bottoms. In winter it migrates to the deeper waters of the coastal zone. Spawning takes place from March to July (Wheeler, 1978, Nijssen and De Groot, 1987, Witte et al., 1991, Muus et al., 1999).
Sand goby is a very common fish found in the coastal waters of the NE Atlantic, North Sea and Baltic.
Sample origin
Fyke and Western Wadden Sea.