Mesogobius batrachocephalus Pallas, 1811
Synonyms: Gobius batrachocephalus, Pallas, 1811; Gobius (Mesogobius) batracocephalus Bleecker, 1874
Common names: Engl: Flat-head goby; Bulg: Stronghil; Rom: Hanus; Russ: Bychok knut; Turk: Kurbaga kayasi baligi; Ukr: Bychok zhaba
Taxonomic descriptions: Two dorsal fins, the second a little longer than the anal fin; no scales on the upper side of the head, the gill covers the throat and bases of the pectoral fins; head flattened and rather pointed with a prominent lower jaw; body of yellowish ground colour; back yellow-brown with 5 broad cross bands; pelvic fins fused by a membrane which also extends across the front of these fins as a skin fold, thus forming a sucking disc; posterior border of the sucking disc well before the vent; none of the dorsal rays sharp and spiny; no lateral line on the sides of the body. Size: maximum - 35 cm; common - about 19 cm (male) and 21 cm (female).
Black Sea Regional level:
Subregion level: LR
Habitats type, Critical habitats, Limiting factors: Brackish water fish inhabiting usually sand and shell grounds, in inshore waters down to a depth of 40 m. Common in coastal waters of the Black and Azov Seas and in the estuaries of the Dnieper, Bug, Dniestr and Don rivers, also in the Bosphorus. Increasing pollution, hypoxia; destruction of breeding grounds (sand covering stony substrates for eggs).
Biology: Feeds mainly on small fishes (sand smelts, anchovies, stripped mullets, scad, gobiids); spends the winter in deeper waters, in April-May migrates towards the shore for reproduction (at 6oC); reaches sexual maturity at three years old. The largest and most tasty goby.
Population trends: Species rather abundant, caught with stake nets and drag seines; in 1989 on the Romanian littoral a total of 23 t, on the Bulgarian littoral - 23 t, and Turkey - 210 t, US - 810 t; their stocks are endangered by periods of hypoxia following algal blooms, when hundreds of specimens are thrown onto beaches; for instance, in August 1989, massive quantities of dead fishes and other organisms were recorded all along the Romanian littoral, 120 t in the tanatocoenose from this species.
Threats: Increasing eutrophication, microalgal blooms followed by hypoxia.
Conservation measures taken: Construction of reefs in the Dniester River estuary which also increased the amount of gobiids.
Conservation measures proposed: Mitigation of anthropogenic intercession; building of different types of artificial reefs; full protection in breeding seasons.
Compiled by: A.Petranu