Gudgeon
Otolith description
Otoliths of cyprinidae are very hard to determine to species level. The otoliths are all round with a remarkable horseshoe shaped sulcus that is directed downwards. The margins are jagged and indented at the ostium.
Five species have otoliths that tend to be somewhat different from the others. Tench Tinca tinca tends to be more oval shaped instead of round, compared to the other cyprinidae. On gudgeon Gobio gobio otoliths the margins tend to be smoother, probably because this is only a small fish and the otoliths are not well developed. Bitterling Rhodeus sericeus is the smallest of the cyprinidae and otoliths are not well developed either. They are smoother at the margins and the sulcus is hardly visible. Roach Rutilus rutilus otoliths have a posterior end that tends to be straight instead of round. The otoliths of rudd Scardinius erythrophthalmus are more jagged and pointed at the ventral margin.
Sizes of otoliths:
gudgeon, bitterling: <2,5 mm
silver bream, roach, rudd: <8 mm
tench, bream, ide: <10 mm
carp: otoliths > 10 mm are always carp otoliths
When eroded the otoliths of all cyprinidae are smoothed, but the sulcus remains visible.
Cyprinidae are a family of fish that have well developed pharyngeal teeth and chewing pads. These are very useful for specific identification of the different fish species (Wheeler, 1978, Veldkamp, 1994, 1995), also because these fish remains are less vulnerable to erosion by the stomach acid.
Pharyngeal teeth description
Pharyngeal teeth of gudgeon have two rows of small teeth, the first with 5 larger teeth (in the photograph one tooth is missing) and the second with 2 or 3 smaller teeth.
Chewing pad description
The chewing pad of gudgeon is rather square, or even wider than long, with an irregular surface on the inside.
Fish length and distribution
Gudgeon can grow up to 20 cm. Gudgeon is a common shooling freshwater fish that is found in many types of fresh waters, but preferring gravel bottoms in clear flowing waters. In summer it is found in shallow waters while in winter they migrate to deeper waters. It spawns at night in shallow waters from May to July (Wheeler, 1978, Nijssen and De Groot, 1987, De Nie, 1996).
Gudgeon is a common fish throughout Europe.
Sample origin
Central and northern parts of the Netherlands.